Englishabsent-minded
adjective
an absent-minded boffin:
forgetful, distracted, preoccupied, inattentive, vague, absorbed, abstracted, unheeding, oblivious, distrait, in a brown study, wool-gathering;
lost in thought, pensive, thoughtful, brooding;
informal scatterbrained, miles away, with a mind/memory like a sieve.
▷antonyms alert, observant.
absent-minded Oxford Dictionary of English