un ‧ think ‧ ing /ʌnˈθɪŋkɪŋ/ BrE AmE adjective
[ Word Family: noun : ↑ think , ↑ rethink , ↑ thinker , ↑ thinking , the unthinkable; verb : ↑ think , ↑ rethink ; adjective : ↑ thinkable ≠ ↑ unthinkable , ↑ thinking ≠ ↑ unthinking ; adverb : ↑ unthinkingly ]
not thinking about the effects of something you say or do
—unthinkingly adverb