An unsuccessful attempt
fiasco, misadventure, nonperformance, abortion, bankruptcy, insolvency, nonsuccess, miscarriage, labor in vain, botch, bungle, frustration, misstep, false step, faux pas, breakdown, malfunction, checkmate, stoppage, collapse, rupture, defeat, rout, overthrow, downfall, implosion, breakdown in communication, total loss, crash, stalemate, negligence, omission, dereliction, no go*, flop*, turkey*, clinker*, loser*, bust*, dud*, washout*, dog*, bomb*, bummer*, lead balloon*, lemon*, flash in the pan*, slip 'twixt the cup and the lip*, losing game*, sinking ship*, sleeveless errand*, louse-up*, mess*, fizzle*, non-starter*.
Antonyms success*, accomplishment, triumph.
An unsuccessful person
incompetent, defaulter, nonperformer, underachiever, ne'er-do-well, scapegrace, prodigal, bankrupt, derelict, castaway, beachcomber, ski bum, loser*, flunker*, born loser*, turkey*, dead duck*, has-been*, also-ran*, lemon*, flop*, bum*, no-account*, dud*, schlemiel*.
Antonyms success*, veteran, star.