1.  eel(n = noun.food) - the fatty flesh of eel; an elongate fish found in fresh water in Europe and America; large eels are usually smoked or pickled;
is a kind of fish
is a part of common eel, freshwater eel
has particulars: smoked eel, elver

2.  eel(n = noun.animal) - voracious snakelike marine or freshwater fishes with smooth slimy usually scaleless skin and having a continuous vertical fin but no ventral fins;
is a kind of malacopterygian, soft-finned fish
is a member of anguilliformes, order anguilliformes, order apodes
has particulars: elver, common eel, freshwater eel, anguilla sucklandii, tuna, moray, moray eel, conger, conger eel

   An elongated fish of many genera and species. The common eels of Europe and America belong to the genus Anguilla. The electrical eel is a species of Gymnotus. The so called vinegar eel is a minute nematode worm. See Conger eel, Electric eel, and Gymnotus. [1913 Webster]

eel, n.
1 any of various snakelike fish, with slender body and poorly developed fins.
2 a slippery or evasive person or thing.

Idiom:
eel-grass
1 any marine plant of the genus Zostera, with long ribbon-like leaves.
2 any submerged freshwater plant of the genus Vallisneria.

Derivative:
eel-like adj. eely adj.

Etymology:
OE {aelig}l f. Gmc

N  convolution, winding, convolution, involution, circumvolution, wave, undulation, tortuosity, anfractuosity, sinuosity, sinuation, meandering, circuit, circumbendibus, twist, twirl, windings and turnings, ambages, torsion, inosculation, reticulation, rivulation, roughness, coil, roll, curl, buckle, spiral, helix, corkscrew, worm, volute, rundle, tendril, scollop, scallop, escalop, kink, ammonite, snakestone, serpent, eel, maze, labyrinth, knot, convoluted, winding, twisted, tortile, tortive, wavy, undated, undulatory, circling, snaky, snake-like, serpentine, serpent, anguill, vermiform, vermicular, mazy, tortuous, sinuous, flexuous, anfractuous, reclivate, rivulose, scolecoid, sigmoid, sigmoidal, spiriferous, spiroid, involved, intricate, complicated, perplexed, labyrinth, labyrinthic, labyrinthian, labyrinthine, peristaltic, daedalian, kinky, knotted, wreathy, frizzly, crepe, buckled, raveled, spiral, coiled, helical, cochleate, cochleous, screw-shaped, turbinated, turbiniform, in and out, round and round, a can of worms, Gordian knot.

blind eel, common eel, conger eel, congo eel, electric eel, freshwater eel, lamper eel, lamprey eel, moray eel, sand eel, sea eel, vinegar eel, wheat eel