Noun thoughtlessness has 2 senses
  1. inconsideration, inconsiderateness, thoughtlessness - the quality of failing to be considerate of others
    --1 is a kind of unkindness
    Antonyms: consideration, considerateness, thoughtfulness
    --1 has particulars: tactlessness; bluntness
  2. unthoughtfulness, thoughtlessness - the trait of not thinking carefully before acting
    --2 is a kind of trait
    --2 has particulars: recklessness, foolhardiness, rashness; impulsiveness