List of thoughtless synonyms and thoughtless related words.
absent-minded, airy, apish, arbitrary, artless, asinine, batty, befooled, beguiled, besotted, blank, blankminded, brainless, brash, buffoonish, calm, capricious, careless, casual, cockeyed, crazy, credulous, cursory, daffy, daft, dazed, degage, discourteous, disregardant, disregardful, distracted, distrait, dizzy, doting, dumb, easygoing, empty, empty-headed, fatuitous, fatuous, featherbrained, featherheaded, feckless, flaky, flippant, fluttery, fond, fool, foolheaded, foolish, forgetful, free and easy, frivolous, fuddled, futile, gaga, giddy, giddy-brained, giddy-headed, giddy-pated, giddy-witted, goofy, grasshopper, gulled, half-assed, happy-go-lucky, harebrain, harebrained, hasty, heedless, hotheaded, idiotic, ill-advised, ill-considered, ill-contrived, ill-devised, ill-gauged, ill-judged, imbecile, impolite, impolitic, improvident, imprudent, inadept, inadvertent, inadvisable, inane, inapt, inattentive, incautious, incogitant, inconsiderate, incurious, indifferent, indiscreet, inefficient, inept, inexpedient, inexpert, infatuated, injudicious, inobservant, insane, insensate, insensitive, insouciant, irrational, kooky, lazy, loony, mad, madcap, maudlin, mediocre, mindless, misadvised, misguided, moronic, myopic, neglectful, negligent, nirvanic, nutty, oblivious, offhand, passive, pedestrian, perfunctory, poor, quietistic, rash, rattlebrained, rattleheaded, rattlepated, reasonless, reckless, regardless, relaxed, remiss, respectless, rude, sappy, scatterbrained, scramblebrained, screwy, selfish, senseless, sentimental, sharp, shatterbrained, shiftless, shortsighted, silly, skill-less, stupid, tactless, thoughtfree, thriftless, tranquil, unaccommodating, unadvised, unapt, uncalculating, uncaring, unceremonious, uncomplaisant, unconsidered, uncooperative, undeft, undexterous, undextrous, undiplomatic, undiscerning, uneconomical, unfacile, unforeseeing, ungracious, unguarded, unheedful, unheeding, unhelpful, unideaed, unintellectual, unintelligent, unmarking, unmindful, unnoticing, unnoting, unobliging, unobservant, unobserving, unoccupied, unprepared, unproficient, unproviding, unready, unreasonable, unreasoning, unreflecting, unreflective, unremarking, unseeing, unsensible, unskillful, unsolicitous, unsound, untactful, unthinking, unthoughtful, unthrifty, unwise, vacant, vacuous, wacky, wet, witless, wrecking