Sustained muscular spasm causing the body to arch forwards, with the head approaching the chest, sometimes occurring in tetanus, certain types of poisoning, etc.; an instance of this. Compare episthotonos , "opisthotonos".
Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. From post-classical Latin emprosthotonos from Hellenistic Greek ἐμπροσθότονος drawn forward and stiffened from ancient Greek ἔμπροσθεν before (from ἐμ-, variant (before a labial) of ἐν- + πρόσθεν before, in front) + τόνος stretching, tension.