desperado, incautious, irresponsible, hectic, audacious, hotheaded, unheedful, brazen, careless, injudicious, daredevil, impulsive, reckless, imprudent, brash, breakneck, impetuous, daring, foolhardy, rash.

reckless, brash, indifferent, careless, inattentive, foolhardy, negligent, wild, frantic, rash, nonchalant, irresponsible, daring, imprudent, heedless, unmindful, hectic.

inattentive, clumsy, remiss, hit-and-miss, inadvertent, forgetful, unmindful, bumbling, negligent, perfunctory, inconsiderate, careless, reckless, slapdash, disregardful, unheedful, slovenly, slipshod, sloppy, haphazard, neglectful, senile, derelict, shoddy.

inane, unthinking, brainless, blank, unreasonable, mindless, unoccupied, unthoughtful, empty-headed, fatuous, vacuous, illogical, vacant.

thankless, heedless, ungrateful, unthankful, unappreciative.

faraway, aloof, negligent, distracted, dreamy, disinterested, wandering, absent, inadvertent, inattentive, heedless, absent-minded, napping, unconcerned, detached, unmindful, uninterested, unconscious, unheedful, disregardful, ignoring, oblivious, befuddled, preoccupied.

puerile, lumpen, absorbed, ungracious, witless, regardless, boorish, feckless, feeble-minded, nutty, incomprehensible, foolish, bewildered, unrefined, selfish, irrational, antisocial, impertinent, dull, insensitive, deaf, self-centered, ill-bred, discourteous, doltish, loony, primitive, babbling, inept, thoughtful, uncaring, lumpish, careful, unaffectionate, heavy-handed, senseless, confused, indiscreet, unreflective, unmannered, unmannerly, uncalled-for, heartless, unhandsome, rational, impersonal, apathetic, shameless, undiplomatic, bovine, unselfish, unheeding, insensible, obtuse, rude, listless, dizzy, disrespectful, stupid, high-handed, egocentric, ill-mannered, heavy, blind, flighty, unconsidered, uncivil, reasoning, sappy, courtesy, careful, abstracted.

The chaste mind of your countess saw nothing in the conduct of the queen but thoughtless simplicity. - "The Scottish Chiefs", Jane Porter.

It was thoughtless in me. - "All's for the Best", T. S. Arthur.

Sabina bit her lip and turned her face away suddenly, for the thoughtless words had hurt her. - "The Heart of Rome", Francis Marion Crawford.

thoughtlessly, thoughtfulness, thoughtlessness, thoroughness, thoughtful, in everyone's thoughts, thornless, thoughtfully, thoroughbreds.