Source : Webster's Revised Unabridged Dictionary (1913)

Batty \Bat"ty\, a.
   Belonging to, or resembling, a bat. ``Batty wings.'' --Shak.

Source : WordNet®

batty
     adj : informal or slang terms for mentally irregular; "it used to
           drive my husband balmy" [syn: {balmy}, {barmy}, {bats},
            {bonkers}, {buggy}, {cracked}, {crackers}, {daft}, {dotty},
            {fruity}, {haywire}, {kooky}, {kookie}, {loco}, {loony},
            {loopy}, {nuts}, {nutty}, {round the bend}, {around
           the bend}, {wacky}, {whacky}]
     [also: {battiest}, {battier}]