Syntactic \Syn*tac"tic\, Syntactical \Syn*tac"tic*al\, a. [Cf. G. ? putting together. See Syntax.]

Of or pertaining to syntax; according to the rules of syntax, or construction. -- Syn*tac"tic*al*ly, adv.

Source: Webster's Revised Unabridged Dictionary (1913)