rat

1 a person who provides information about another's wrongdoing the drug mule refused to turn rat without a guarantee of immunity Synonyms betrayer, canary [slang], deep throat, fink, informant, nark [British], informer, rat fink, snitch, snitcher, squealer, stoolie, stool pigeon, talebearer, tattler, tattletale, telltale, whistle-blowerRelated Words collaborator; blabber, blabbermouth, gossip, gossiper, leaker; snoop, snooper, spy; notifier

2 someone who regularly spends time in a particular place on Friday night the mall rats were out in full force Synonyms familiar, frequenter, habitué (also habitue), haunter, denizen, regularRelated Words client, customer, guest, patron; addict, aficionado (also afficionado), buff, bug, devotee, enthusiast, fan, fanatic, fancier, fiend, freak, lover, maniac, nut

3 a person whose behavior is offensive to others no one can understand what she finds appealing in a rat like him Synonyms bastard, beast, bleeder [British], blighter [chiefly British], boor, bounder, bugger, buzzard, cad, chuff, churl, clown, creep, cretin, crud [slang], crumb [slang], cur, dirtbag [slang], dog, fink, heel, hound, joker, louse, lout, pill, jerk, rat fink, reptile, rotter, schmuck [slang], scum, scumbag [slang], scuzzball [slang], skunk, sleaze, sleazebag [slang], sleazeball [slang], slime, slimeball [slang], slob, snake, so-and-so, sod [chiefly British], stinkard, stinker, swine, toad, varmint, verminRelated Words barbarian, brute, caveman, Neanderthal, savage; loudmouth, vulgarian; lowlife, miscreant, rascal, rogue, roughneck, scab, scamp, scoundrel, villain, wretch; booby, doofus [slang], fool, jackass, nincompoop, ninny, nit [chiefly British], nitwit, nut, schmo (or schmoe) [slang]; airhead, birdbrain, blockhead, dink [slang], dolt, dope, dork [slang], goon, half-wit, idiot, imbecile, moron, turkey; brat, insolent, nuisance, pest, snip; snob, snoot, snot; dweeb [slang], nerdNear Antonyms hero, heroine, idol, role model; gentleman, lady; angel, saint