Use 'unthinking' to describe actions or remarks when someone ignores others' feelings. He made unthinking comments without realizing how much they would offend.
Pro Tip 2/3
Negative Outcome
'Unthinking' often implies that someone's lack of consideration resulted in a negative impact. Her unthinking choice to share the secret strained their friendship.
Pro Tip 3/3
Beyond Intention
Describe actions as 'unthinking' when the person didn't mean to cause harm. His unthinking neglect of the plants led to them wilting.