anguilliformes

from The Century Dictionary.

• In Cuvier's classification of fishes, the only recognized family of Malacopterygii apodes, including fishes with an elongated form, a thick and soft skin, few bones, no cæca, and in most cases a swim-bladder which is often of singular shape. It has been disintegrated into many families, and even different orders.

from the GNU version of the Collaborative International Dictionary of English.

• noun an order of elongate fishes with pelvic fins and girdle absent or reduced.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun elongate fishes with pelvic fins and girdle absent or reduced