1. [adj]  lost in thought; showing preoccupation; "an absent stare"; "an absentminded professer"; "the scatty glancing quality of a hyperactive but unfocused intelligence"
2. [adj]  lacking sense or discretion; "his rattlebrained crackpot ideas"; "how rattlepated I am! I've forgotten what I came for"- Glenway Westcott

SCATTY is a 6 letter word that starts with S.