Source : Webster's Revised Unabridged Dictionary (1913)

Dotty \Dot"ty\, a. [From 2d {Dot}.]
   1. Composed of, or characterized by, dots.

   2. [Perh. a different word; cf. {Totty}.] Unsteady in gait;
      hence, feeble; half-witted. [Eng.]

Source : WordNet®

dotty
     adj 1: informal or slang terms for mentally irregular; "it used to
            drive my husband balmy" [syn: {balmy}, {barmy}, {bats},
             {batty}, {bonkers}, {buggy}, {cracked}, {crackers}, {daft},
             {fruity}, {haywire}, {kooky}, {kookie}, {loco}, {loony},
             {loopy}, {nuts}, {nutty}, {round the bend}, {around
            the bend}, {wacky}, {whacky}]
     2: marked by foolish or unreasoning fondness; "she was crazy
        about him"; "gaga over the rock group's new album"; "he
        was infatuated with her" [syn: {crazy}, {gaga}, {enamored},
         {infatuated}, {in love}, {smitten}, {soft on(p)}, {taken
        with(p)}]
     [also: {dottiest}, {dottier}]