Where does “ακαμψία” come from?

ακαμψία (Greek) comes from Ancient Greek ἄκαμπτος, from Ancient Greek ἀ-, from Proto-Hellenic hə-, from Proto-Indo-European sm̥-, from Proto-Indo-European sem- — together, one.

ακαμψία (Greek): rigidity, inflexibility; stiffness;...