Where does “ψυχραιμία” come from?

ψυχραιμία (Greek) comes from French sang-froid, from French sang, from Old French sanc, from Vulgar Latin sanguem, from Latin sanguinem, from Latin sanguen, from Latin san-, from Proto-Indo-European h₁sh₂-én- — blood.

ψυχραιμία (Greek): sangfroid, composure