Fundamental Fly Fishing Terminology

Fly fishing is immersive. No, we’re not talking about getting dunked in a river as a rite of initiation. We’re talking about the way we see our favorite sport as a culture, and as with learning any new way of life, you’ve got to speak the language. Here’s a glossary of fundamental fly-fishing terminology to get you started. For next-level learning, keep an eye on the AvidMax Blog for introductory guides to fly tying, equipment components, and on-the-water fly-fishing techniques.


Action: A term describing a rod’s flexion and ability to store and release energy. See “loading/unloading”.

Anadromous: Fish species that hatch in freshwater, mature in saltwater, and return “home” to spawn. Commonly referred to as “sea-run”.

Attractor fly: A “generalist” pattern designed to roughly mimic the silhouette or color of the natural prey species. Attractors tease fish into indiscriminate striking behavior, rather than selective feeding responses. Opposite of “imitator”. Usually showier and more exaggerated than “impressionistic” flies (see below).

Arbor: A fly reel spool’s center around which backing and line is wound.

Aquatics: Species of insects or animals that live in the water for most or all their lives. Crawdads, leeches, and minnows are referred to as aquatic, and so are midges, caddisflies, stoneflies, and mayflies, whose larvae, pupae, or nymphs are water-bound.


Back cast: The part of the cast during which the rod tip is pointing away from the target area. The angler’s “backswing”.

Backing: Strong braided or monofilament line connecting the fly line to the arbor. Acts as a “reserve” after the more expensive fly-fishing line has been fed out during a long run by an enthusiastic fish.

Blank: The “chassis” of a fly rod before the addition of its components and finish. Rods are “built” on blanks.

Boil: A temporary “bump” on the water surface caused by a sudden direction change (usually downward) after a fish has either missed or refused the fly.

Break off: The loss of a fish due to a broken line or weak knot.

Butt section: The thick “back” end of a leader, where it attaches to the fly line. Also, the very end of a fly rod, behind the reel seat.


Casting arc: The rod’s range of travel throughout a single cast. Usually measured by positions on the clock. For example, the back cast to 11:00 and the forward cast to 2:00.

Chironomid: The non-biting insect family within the Diptera (midge) taxonomic order; an essential fly-fishing insect group.

Click-drag: The mechanical component of a reel that moderates line payout, allowing for better control when “fighting” the fish.

Complete metamorphosis: A life cycle containing four main stages: egg, larvae, pupae, adult. Caddisflies are among many aquatic species referred to as having a complete metamorphosis.

Covering the water: The practice of executing a series of casts fanning out from one side of the angler to the other, making the most efficient use of the angler’s position. 


Dead drift: Fishing a fly with no tension on the leader or tippet.

Diptera: A very large taxonomic order of insects, of which adults have two wings. Includes craneflies, midges, and mosquitoes.

Drag: As “click-drag”, the adjustable mechanism in the reel that restricts line feed while the angler retrieves or tires a fish. Also, the force against a fly when the tippet and leader have become taught.

Dropper: A small nymph tied beneath a dry fly, or beneath a wet fly or other floating material suspended higher in the water column. (See “indicator”).

Dry fly: Fly patterns designed to sit on the top of or partially in the water’s surface tension.

Dun: A newly-emerged mayfly before it’s ready to breed, usually spending its time drying its wings on the surface of pools or on nearby foliage. The entomological term is “sub-imago”. Also, a class of dry fly patterns designed to imitate sub-adults.


Eddy: Swirling “whirlpools” caused by opposing currents or water disturbances.

Emerger: A reference to an insect as it transitions from the aquatic to aerial phase, shedding its nymphal shuck (exoskeleton). Emerger patterns vary between floating nymphs or pupae, nymphs or pupae with wings coming out of the shuck, and crippled young adults.

Entomology: The science and study of insects. We recommend Philip Rowley’ extensive online entomology guide for flyfishing.


False cast: The action of casting without allowing the fly to land on the water. A method for feeding out the line while it’s airborne, adjusting aim, or showing off to bystanders.

Floatant: A waxy or oily product that repels water, allowing dry flies, lines, and leaders to float. 

Fluorocarbon: A dense, strong fishing line, leader, or tippet made from polyvinylidene fluoride. “Fluoro” has a refractory index close to that of water, making it all but invisible to fish. Fluorocarbon, due to its density, sinks faster than nylon lines.

Forward cast: The forward and final movement of the rod that “shoots” the line outward.

Foul hook/foul catch: When a fish is hooked anywhere but the mouth. Also called “snagging” a fish. Intentional snagging is illegal in most waters, though some management agencies allow a specific season for the practice.

Freestone stream: One that originates from above-the-ground alpine sources, including rain, snowpack, and glacial ice. Beds are typically gravelly or stone-covered due to slow erosion or glacial pressure.


Glide: See “run”.

Going Barbless: Fishing without a barbed hook, or one that’s been pinched flush.

Grip: A forgiving material (usually cork) covering the area immediately forward of the reel. Shaped for ergonomic and slip-free handling.


Hatch: The simultaneous emergence of a large number of insects of the same species.

Headwaters: The origins of a stream or river; usually drainage fed by smaller runoff streams, springs, or glacial melt.

Haul: A technique in which the hand not holding the rod manipulates the line for the purpose of adding power to the cast. Double and triple hauls are common variations.

Hydrology: The science and physics of water movement. The USGS introduction to hydrology and glossary will help you understand the fish’s natural environment, “read the water”, and understand flow and condition reports.


Imitator fly: A pattern designed to closely mimic a natural species or subspecies. Often fished in high-visibility water or whenever the fish are easily spooked and/or feeding exclusively on a certain insect. Use imitators to “match the hatch”.

Impressionistic: Fly patterns designed to imitate a wider class and profile of natural insects rather than a species. Similar to attractors, but usually more subtle.

Incomplete (or simple) metamorphosis: A three-stage transition from egg to nymph to adult: Mayflies are insects with incomplete metamorphosis.

Indicator (also strike indicator or sight bob): Lightweight floating material attached to the leader to alert angler of a fly “sipping” a nymph. Also helps position the nymph at the correct position in the water column, and signals direction of undercurrents. Some dry flies serve as effective indicators. Here’s a great article about nymphing with indicators.


Jump/jumping rise: When the fish (typically a trout) leaps from the water to catch insects just above the water surface. An indication that a hatch is underway. (See “rise” below.)


Keeper: A thin loop of wire embedded into the underside of the rod, just forward of the grip. Where one hooks the fly (and thus the line) when not actively casting. Also, a fish that meets the legal requirements for possession.


Larvae: The first stage in the complete metamorphosis lifestyle. Visit this gallery for photos of various caddis larvae.

Leader: The monofilament or fluorocarbon line between the fly line and the tippet.

Lie: A spot in a stream that doesn’t require much exertion on the part of the fish and provides low-effort feeding opportunities. Also, any fishing story not backed up by photos or video.

Line weight: The weight of a fly line’s first 30′, as measured in grains (one grain = 64.79891 milligrams). The first 30′ of a 7wt line is 185 grains, therefore, the number 7 is a classification rather than the actual weight. Rods, reels, and lines are matched according to the line’s weight designation.

Loading and unloading (the rod): Storing and releasing energy on the rod through the motion of casting. As the rod bends, it loads and stores energy. The cast and straightening of the rod unloads energy, launching the lure and line toward its target.


Mayfly: Aquatic fly of the Ephemeroptera order, with an upwardly-curved “butt”, two or three long, hair-like tails, and two pairs of wings – large, broad forewings and much smaller but similarly-shaped hindwings. The wings “tent” vertically above the insect-like sails, or like those of resting butterflies.

Mending the line: Lifting and laying down the line after a cast to increase slack and avoid drag.

Midge: A generic term for small, two-winged insects; common name for the Diptera order.

Monofilament/mono: A single, unbraided thread of nylon used for leaders, tippets, and—in other angling methods—primary fishing lines.


Natural: A reference to the species of insect a pattern is designed to imitate. “The fish are rising to the naturals but ignoring my fly.”

Nymph: The aquatic stage of species that undergoes incomplete metamorphosis (mayflies, stoneflies). Nymphs often go through several molts as they develop. See “incomplete metamorphosis”.

Nymphing: Fishing nymph, pupae, and some emerger patterns at various sections of the water column.


Open loop: The shape of the line created by a sloppy cast with an exaggerated arc.


Palming the reel: The act of putting your fingers or pad of your palm on the reel’s spool; a way to assist the reel’s drag mechanism with a bit of finesse.

PB: Short for an angler’s “personal best” catch within a species; often used on fishing forums or written on photos posted on fly shop “brag boards”.

Pick up & lay down: A brisk, single-arc cast to straighten or adjust the position of a line.

Pocket: A patch of still water, usually on the downstream side of a rock, trunk, bridge pile, or other obstacle around which the water can flow. Also, the part of your vest from where your camera falls into the water the minute you net your PB steelhead.

Presentation: The manner in which you “set down” the fly as naturally as possible, taking into account the current and the position of the target fish.

Pupae: Insects that undergo complete metamorphosis, such as midges and caddisflies, transition to adults from the pupae stage, which is preceded by the larval stage.


Reach cast: A cast that releases extra slack at the end of the line.

Redd: A shallow indentation in a stream bed in which trout or salmon lay and fertilize eggs. Bass nests are called “beds”.

Retrieve: The act of gently pulling or tugging a cast fly for better positioning, or to simulate movement. Also, to “reel in” the line. Reels are designated “left-hand retrieve” or “right-hand retrieve”.

Riffle: A small rapid in moving water, with or without whitecaps. Usually created by shallower, rough stream beds.

Rise: The act of a fish coming to the surface to feed. When rising, fish may barely disturb the surface, “sipping” the insect or fly.

Rock snot: Refers to slimy algae on submerged rocks, but more accurately assigned to Didymo (Didymosphenia geminata) a non-native, fibrous, mat-forming diatom. Didymo can spread to uncontaminated waters if waders, boots, and gear aren’t cleaned and dried in between use. One of a number of species that has forced several states and wildlife departments to ban felt-soled wading boots.

Roll cast: A technique used when a back cast is impossible due to trees or other obstacles directly above and/or behind the angler.

Run: A stream section of varying widths and currents that is deep enough to not cause significant riffles, and often channels prey species downstream. Synonymous with “glide”. Or, when a hooked fish swims (“runs”) away from the angler, causing the reel to feed out line.


S-cast: A lateral flourish on the forward cast that causes the line to create an “s” on the surface; the purpose is to create a significant amount of slack without having to further disturb the water.

Seam line: The point at which currents traveling in different directions or at different speeds meet.

Spey: A style of fly fishing using a long, two-handed rod.

Spinner: The second and final phase of an adult mayfly’s life cycle, usually with significantly different colors than the post-emergent dun phase due to a transitional molt. Spinners are ready to mate, often forming clouds over the water. In entomology, this is the “imago” phase.

Spinnerfall: A large die-off of adults after mating and egg-laying; the water surface will be dotted with spent females, their wings spread flat. Fish will stuff themselves on spinners, subtly sipping them from the surface.

Spool: The (usually) removable, non-mechanical section of a fly reel to which the backing is tied.

Streamer: Typically among the larger, more colorful wet flies, designed to imitate leeches, baitfish, crawdads, and other aquatic prey. Most often tied with marabou, fur, or long tufts of animal hair. Useful year-round.

Stripping: Tugging in the line to simulate natural fly movement. Also, a means by which some anglers fund their fishing adventures.

Stonefly: An insect with a long body and two wings that “stack” and lay flat against the full-length abdomen. Stoneflies require pristine, oxygen-rich water. Stonefly nymphs crawl out of the water onto rocks before shedding their nymphal shucks.

Swinging: The act of casting a fly across a stream and well in front of a fish, allowing the fly to drift in an arc across the fish’s feeding area.


Tailwater: A body of water flowing from a dam’s outlet.

Tenkara: A Japanese style of fly fishing using only a telescoping rod, line, and fly. Read about Tenkara fishing and why it’s becoming popular among fly anglers of all skill levels.

Terrestrials: Insects or bait species that spend their entire life cycles on land, i.e. grasshoppers, mice, ants, and bees.

Tippet: Thin monofilament or fluorocarbon line that attaches to the leader at one and, and to the fly at the other.

Turnover: The point at which the rod tip changes direction during the cast.


Variant/variation: A “tweak” to a standard fly pattern, usually involving an altered size proportion.

Vest: The multi-pocketed, wearable storage system that contains everything you need for fishing trout on the day you happen to be fishing for bass.


Wader belt: A snug strap around the waist of one’s waders to prevent them from filling up and weighing down a fallen angler. Never wade without one.

Wet fly: Any pattern that imitates an insect in its aquatic phase. Patterns also imitate baitfish, crawdads, and other non-insect aquatic species. Typically fished anywhere from beneath the water’s surface film to the stream bottom.

Wind knot: Among the first fishing knots a novice will master. A wind knot is any tangle in the leader or tippet, so named because casting into the wind increases the odds of experiencing one.


“X”: A classification symbol representing tippet and leader diameter. As with fly line, it’s counter-intuitive. The number next to the X represents the filament’s diameter, and smaller numbers represent larger diameters. For example, a 0X line has a .011″ diameter, and 6x is .005″ across.


Zinger: Retractable cord pinned to a vest or waist pack on one end, and (usually) line nippers on the other. Also, a witty insult aimed at your fishing buddy.

Z-Lon: Brand name for a popular fly-tying yarn fiber. Also useful for making strike indicators.

4 thoughts on “Fundamental Fly Fishing Terminology

  1. Hey now – this is surely going to be a handy reference. I wish this was around when I was brand new to fly fishing/tying! But it’s true we are all wanting to learn more so I hope this glossary grows too!

    All the best – Freddy!

    1. Thanks Freddy. Yes, it’s definitely a great start. There are so many terms, that we hope to continue to add to this list as time goes on.

  2. This is terrific! Extra kudos to the author because this is absolutely fantastic! I wish I had had this when I first started out fly fishing.

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