1. (a.) Not thinking; not heedful; thoughtless; inconsiderate; as, unthinking youth.

2. (a.) Not indicating thought or reflection; thoughtless.

airy arbitrary automatic blank blankminded blind brainless calm capricious careless casual compulsive conditioned crazy cursory degage discourteous disregardant disregardful easygoing empty empty-headed fatuous feckless flippant foolish forced forgetful free and easy hasty headless heedless idiotic ignorant ill-advised ill-considered ill-contrived ill-devised ill-gauged ill-judged illogical imbecilic impolite impolitic imprudent impulsive inadvertent inadvisable inane incogitant inconsiderate indifferent indiscreet inept inexpedient injudicious insane insensate insouciant instinctive involuntary irrational lackbrained lazy lean-minded lean-witted mad mechanical mindless misadvised misguided moronic myopic neglectful nirvanic nonsensical not bright oblivious of little brain offhand passive pea-brained perfunctory pin-brained quietistic rash reasonless reckless reflex reflexive regardless relaxed respectless rude senseless short-sighted shortsighted silly slackminded slackwitted stupid tactless thoughtfree thoughtless tranquil unaccommodating unadvised uncalculating uncaring uncivil uncomplaisant unconscious unconsidered uncooperative undesigned undiplomatic undiscerning undiscriminating unforeseeing ungifted unguarded unguided unheedful unheeding unhelpful unideaed unintellectual unintelligent unintended unintentional unmeant unmeditated unmindful unobliging unoccupied unperceiving unperceptive unplanned unpremeditated unprepared unprompted unpurposed unready unreasonable unreasoning unreflecting unreflective unseeing unsensible unsolicitous unsound untactful untalented unthought-of unthoughtful unwilled unwilling unwise unwitting vacant vacuous witless wrecking