opisthotonos
From LSJ
τραχὺς ἐντεῦθεν μελάμπυγός τε τοῖς ἐχθροῖς ἅπασιν → he is a tough black-arse towards his enemies, he is a veritable Heracles towards his enemies
Latin > English (Lewis & Short)
ŏpisthŏtŏnos: i, m., = ὀπισθότονος>,
I a disease in which the body is violently curved backwards, a form of lock-jaw (post-Aug.), Plin. 28, 12, 52, § 192; 23, 1, 24, § 48 (written as Greek, Cels. 4, 3, § 3).—
II A disease that causes a person to fall backwards (eccl. Lat.), Hier. 3 Ep. ad Ephes. 6, 4.