irreflexivo in English:

How thoughtless of you to do that.

It occurs to me that I have been thoughtless.

The movie star ate crow many times because of all the thoughtless things she said.

a thoughtless person

He had behaved thoughtlessly and selfishly. I should have called her to say we'd be late - it was a bit thoughtless of me.

Fear made people do thoughtless things that often got them into trouble.

It was thoughtless not to call and say you'd be late.

How could you be so... thoughtless?

Thoughtless speech may give rise to great mischief.

I sensed with discomfort that the two of them might ridicule me behind my back as a thoughtless, simple-minded satyr.