Feathering 
A wave state just prior to the wave breaking, when the crest begins to show a little whitewater as the wave face steepens. Most often seen in offshore wind conditions.

Fiberglass
The woven glass cloth that is saturated with resin, which is used in surfboard lamination to produce the hard outer surface of a surfboard.

Fin
A) Rudderlike device(s) used beneath a surfboard to assist control, direction and drive. Many different fin shapes are possible, but most are designed to resemble a dolphin's dorsal fin. Today fins are mostly used in groups of three-two ahead, one behind-a configuration known as a Thruster (see Thruster). They're also used, less frequently, in pairs or singles. B) Rubber swim fins worn on the feet of body boarders and body surfers to help catch waves in deep water. Surfing A-Z

Fin System
A catchall phrase referring to various inventions allowing fins to be attached and removed easily and quickly, i.e., Fin Control Systems.

Firing
Really good surf. Also called pumping, or going off.

Fish
A surfboard design invented by Steve Lis of San Diego, California, which features a wide nose and broad swallow-type tail design, with a twin-fin setup; in recent years, refers to almost any short, stubby, wide surfboard. Surfing A-Z

Flat
When there are no waves to surf. Unridable surfing conditions. Some waves also have "flat" sections, which are mushy and powerless.

Flatstitched
(flatlocked) Seams which have the stitching sewn through the material; generally usually used in warmer-water suits because-though it's super flexible-it does let water through.

Floater
 Floater-A maneuver in which the surfer rides over and/or along the top of a breaking wave, sliding across broken foam or a pitching lip, then drops back down into the main part of the wave. So named due to the floating weightless sensation induced by the move. Advanced surfers may finish the move with a free-fall down with the lip of the wave as it breaks. Surfing A-Z

Foam
1) The liquid polyethylene material used to mold surfboard blanks, which hardens or cures into a soft but firm foam, and is then shaped by hand. 2) Also the white water of a breaking wave and/or the bubbles left over from a breaking wave.

Foil
1) The rate of change of thickness from nose to tail of a surfboard. 2) The rate of change of thickness of a surfboard fin from its front to its back edge. Surfing A-Z

Forehand
(see frontside)

Forerunners
1.5 times the swell period to be exact.

Forward Vee
(see reverse vee)

Freeboarding
Generally refers to the act of riding a surfboard behind a boat, similar to water skiing. Tow-in surfing's humble origins. Surfing A-Z

Frontside
Facing the wave while surfing. A goofyfoot going left or a regularfoot going right. Also called forehand.

Fujiwara Effect
When two tropical cyclones rotate about each other. This is caused by the lack of steering winds in the upper atmosphere so the cyclones actually end up affecting each other.

Fullsuit
As the name implies, a wetsuit that covers the whole body. (Though some companies make short-arm fullsuits) Ranges in thickness from 2mm to 6mm, but the most common fullsuits are 3/2mm and 4/3mm. (Called "steamer" in Australia.)

Funboard
A compromise surfboard design, combining the superior paddling attributes of a longboard, but stripped of some of the unwieldy length and bulk so the rider may have a taste of shortboard maneuverability. Surfing A-Z

El Nino
A warming of the ocean surface in the Eastern Pacific that begins off the western coast of South America. The warmer water can greatly enhance tropical cyclone development in the Central Eastern Pacific, as well as wintertime storms throughout the North Pacific due to the contrast between the warm water and cold air. The North Pacific jet stream and storm tracks shift further south which generates more wind, swell, and stormy conditions in California, while the areas further north experience milder weather. For more see Surfing A-Z.

Energy
A unit of measurement for the power in a wave. Usually in meters squared or centimeters squared.

Entry
A term used to describe the area of the surfboard where water first comes into contact with the rocker.

Entry line
The line a surfer will draw when dropping into a wave.

Epoxy
A type of plastic resin used by some manufacturers in place of polyester resin. Usually an epoxy-user also uses a polystyrene blank, which can be badly affected by polyester resins.

Expanded Seam Technology (EST)
Developed by a skin graft specialist in the late '90s, EST is a way to have a "stitchless" suit by weaving the panels together in hexagonal patterns; touted a few years back as the next giant thing, now mainly used in super cold water suits.

Exposure
A term used to describe how breaks within a region will pick up an incoming swell relative to whether they face the incoming swell or not. For example, if you have three breaks facing different directions: break #1 faces south. Break #2 faces southwest. Break #3 faces northwest. Now if we have a incoming S swell: Break #1 would be the best-exposed, #2 would be partially exposed and would most likely be consider average, it would get enough energy to break but not as much as the first beach. Break #3 would be facing away from the swell and would not break.

Extratropical
A term used to indicate that a tropical cyclone has lost its "tropical" characteristic-a warm core center that was the storm's primary energy source. Once "going extratropical" the remains of the tropical cyclone often merges with a cold "winter type" cyclone. The resulting effect of mixing the remnants of warm tropical air with cold air creates a "combustible" type of weather system, which often supercharges the storm with very intense wind speeds and extremely large waves. Extratropical storms usually happen in the fall when late season tropical cyclones converge with early winter storm systems. The storm in the movie "Perfect Storm" was a classic example of an October extratropical storm.

Eye
A relatively calm area found near the center of storms, primarily hurricanes and typhoons. Also termed as the "eye of the storm". In hurricanes or typhoons, the eye is either completely or partially surrounded by the eyewall cloud.

Eyewall/Wall Cloud
A deep, thick band of clouds that surround the eye or center of a tropical cyclone.