[adjective]Thoughtless means not carefully considering the effect of your actions.It was thoughtless not to phone and say you'd be late.I'm sorry I said that about his mother - it was very thoughtless of me.She's not intentionally unkind - she's just a little thoughtless sometimes.
THOUGHTLESS
Meaning of THOUGHTLESS in English
Cambridge English vocab. Кембриджский английский словарь. 2012