Syn`en·tog'na·thi noun plural [ New Latin , from Greek sy`n with + 'ento`s within + gna`qos jaw.] (Zoology) An order of fishes, resembling the Physoclisti, without spines in the dorsal, anal, and ventral fins. It includes the true flying fishes. Found on http://www.encyclo.co.uk/webster/S/266