scatty

adjectives

lacking sense or discretion

"his rattlebrained crackpot ideas"; "how rattlepated I am! I've forgotten what I came for"- Glenway Westcott

lost in thought; showing preoccupation

"an absent stare"; "an absentminded professor"; "the scatty glancing quality of a hyperactive but unfocused intelligence"

absent, absentminded, abstracted, scatty