completely engrossed in thought; absorbed.

previously occupied; taken; filled.

Biology . already used as a name for some species, genus, etc., and not available as a designation for any other.

adjective

observant , thoughtful , unoccupied

adjective

absent , absent-minded , absorbed , abstracted , airheaded , asleep * , bemused , bugged , daydreaming , deep * , distracted , distrait , engaged , engrossed , faraway , fascinated , forgetful , have on the brain , heedless , hung up * , immersed , inconscient , intent , lost , lost in thought , mooning , moony , oblivious , obsessed , rapt , removed , spellbound , spread out , taken up , unaware , woolgathering , wrapped-upnotes:occupied means in use or seized and controlled as by military invasion; preoccupied means deeply absorbed in thought or having compulsive concern with something , deep , inattentive , absentminded