lost in thought; showing preoccupation; "an absent stare"; "an absentminded professer"; "the scatty glancing quality of a hyperactive but unfocused intelligence"
If you describe someone as scatty, you mean that they often forget things or behave in a silly way. Her mother is scatty and absent-minded. = scatterbrained. someone who is scatty often forgets or loses things because they are not sensible or practical (Probably from scatterbrained)