perspiration (n.)

1610s, from French perspiration (1560s), noun of action from perspirer "perspire," from Latin perspirare "blow or breathe constantly," from per "through" (from PIE root *per- (1) "forward," hence "through") + spirare "to breathe, blow" (see spirit (n.)). Applied to excretion of invisible moistures through the skin (1620s), hence used as a euphemism for "sweat" from 1725.