thoughtless

thoughtless adjective absent-minded, abstracted, blank, blockish, careless, casual, dazed, disregardful, distrait, dull, flighty, foolhardy, giddy, headlong, heedless, ill-advised, improvident, imprudens, imprudent, impulsive, inadvertent, inane, inattentive, incogitant, inconsiderate, inconsultus, indifferent, indiscreet, insensate, irrational, neglectful, neglegens, negligent, precipitate, rash, reckless, regardless, remiss, scatterbrained, selfish, tactless, unaccommodating, unconcerned, unobliging, unobservant, unreasoning, unreflecting, unreflective, unthinking, unthoughtful, unwatchful, vacuous, without consideration

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See also: blind, careless, casual, cursory, derelict, fatuous, heedless, hot-blooded, ill-judged, impolitic, improvident, imprudent, impulsive, inadvertent, injudicious, irrational, irresponsible, lax, misadvised, negligent, oblivious, perfunctory, perverse, precipitate, reckless, remiss, slipshod, unpremeditated, unwitting, vacuous