derelict

1 failing to give proper care and attention the guards were judged derelict in their duty Synonyms careless, negligent, disregardful, lax, lazy, neglectful, neglecting, remiss, slackRelated Words heedless, incautious, irresponsible, reckless, wild; unguarded, unwary; forgetful; disregardful, disregarding, inattentive, oblivious, thoughtless, unheeding, unmindful, unthinking; apathetic, disinterested, indifferent, unconcerned, uninterested; delinquent; looseNear Antonyms meticulous, painstaking, punctilious; cautious, chary, circumspect, gingerly, guarded; alert, heedful, heeding, mindful, observant, regardful, regarding, vigilant, wary, watchful; foresighted, forethoughtful, provident, responsible; thinking, thoughtful; concerned, interestedAntonyms attentive, careful, conscientious, nonnegligent

2 left unoccupied or unused an old derelict mansion that was rumored to be haunted Synonyms abandoned, deserted, desolate, disused, forgotten, forsaken, rejected, vacant, vacated, voidRelated Words ignored, neglected, unattended, untended; castaway, cast-off, discarded, jettisoned, junked, refuse, waste; godforsaken, miserable, shabby, wretched; empty, idleNear Antonyms reclaimed, recovered, redeemed, rescued, retrieved, salvaged, saved; reconditioned, rehabbed, rehabilitated, restored; repeopled