A person or animal that is markedly unusual or deformed.

synonyms: lusus naturae, monster, monstrosity.

Roget 83: nonconformity etc. 82; unconformity, disconformity; unconventionality, informality, abnormity^†, abnormality, anomaly; anomalousness etc. adj.^†; exception, peculiarity; infraction of law, breach, of law, violation of law, violation of custom, violation of usage, infringement of law, infringement of custom, infringement of usage; teratism^†, eccentricity, bizarrerie^†, oddity, je ne sais quoi [Fr.], monster, monstrosity, rarity; freak, freak of Nature, weirdo, mutant; rouser, snorter [U.S.].    individuality, idiosyncrasy, originality, mannerism.    aberration; irregularity; variety; singularity; exemption; salvo etc. (qualification) 469.    nonconformist; nondescript, character, original, nonesuch, nonsuch^†, monster, prodigy, wonder, miracle, curiosity, flying fish, black sheep, black swan, lusus naturae [Lat.], rara avis [Lat.], queer fish; mongrel, random breed; half-caste, half-blood, half-breed; metis [Lat.], crossbreed, hybrid, mule, hinny, mulatto; tertium quid [Lat.], hermaphrodite.    [Mythical animals] phoenix, chimera, hydra, sphinx, minotaur; griffin, griffon; centaur; saggittary^†; kraken, cockatrice, wyvern, roc, dragon, sea serpent; mermaid, merman, merfolk^†; unicorn; Cyclops, men whose heads do grow beneath their men whose heads do grow beneath their shoulders" [Othello]; teratology.    [unconformable to the surroundings] fish out of water; neither one thing nor another, neither fish nor fowl, neither fish flesh nor fowl nor good red neither fish flesh nor fowl nor good red herring; one in a million, one in a way, one in a thousand; outcast, outlaw; off the beaten track; oasis.    ... show more

Roget 608: caprice, fancy, humor; whim, whimsy, whimsey^†, whimwham^†; crotchet, capriccio, quirk, freak, maggot, fad, vagary, prank, fit, flimflam, escapade, boutade [Fr.], wild-goose chase; capriciousness etc. adj.; kink.    ... show more

Dutch: misbaksel, misvorming, monstertje, monstruositeit, wangedrocht, wanproduct, wanprodukt

Someone who is so ardently devoted to something that it resembles an addiction:
— A bodybuilding freak.

synonyms: addict, junkie, junky, nut.

Lose one's nerve:
— When he saw the accident, he freaked out.

synonyms: freak out, gross out.