noun, plural (especially collectively) flat·fish, (especially referring to two or more kinds or species) flat·fish·es.

any fish of the order Heterosomata (Pleuronectiformes), including the halibut, sole, flounder, etc., having a greatly compressed body and swimming on one side, with both eyes on the upper side in the adult.

Origin of flatfish

First recorded in 1700–10; flat1 + fish
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for flatfish

Historical Examples of flatfish

  • And thinkin' no more of it than I would of—of scalin' a flatfish.

    Galusha the Magnificent

    Joseph C. Lincoln

  • We knew we'd no business to be there and we felt as foolish as flatfish.

  • There I was, caught in a trap, and made a prisoner by a flatfish.

    Peter Simple

    Frederick Marryat

  • They breathed heavily through their noses and stared straight in front of them—impassive as flatfish.

    From Sea to Sea

    Rudyard Kipling

  • Saint Petersburg is very ill supplied with salt-water fish; there are neither lobsters nor flatfish.

    Fred Markham in Russia

    W. H. G. Kingston

British Dictionary definitions for flatfish


noun plural -fish or -fishes

any marine spiny-finned fish of the order Heterosomata, including the halibut, plaice, turbot, and sole, all of which (when adult) swim along the sea floor on one side of the body, which is highly compressed and has both eyes on the uppermost side
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for flatfish

1710, from flat (adj.) + fish (n.).

Online Etymology Dictionary, © 2010 Douglas Harper