Source : Webster's Revised Unabridged Dictionary (1913)

Wigwag \Wig"wag`\, v. i. [See {Wag}, v. t.] (Naut.)
   To signal by means of a flag waved from side to side
   according to a code adopted for the purpose. [Colloq.]

Wigwag \Wig"wag`\, v. t. & i. [imp. & p. p. {Wigwagged}; p. pr.
   & vb. n. {Wigwagging}.]
   To move to and fro, to wag.

Wigwag \Wig"wag`\, n. [See {Wigwag}, v. t. & i.]
   Act or art of wigwagging; a message wigwagged; -- chiefly
   attributive; as, the wigwag code. -- {Wig"wag`er}, n.

Source : WordNet®

wigwag
     v 1: send a signal by waving a flag or a light according to a
          certain code
     2: signal by or as if by a flag or light waved according to a
        code
     [also: {wigwagging}, {wigwagged}]