humidity comes from Old French humidite, from Latin humiditas, from humidus/umidus ('moist'), from umēre ('to be wet'). The path is chiefly one of transmission: the word passes through the named languages and forms, with each stage preserving part of the modern shape. In present English, the noun sense is "the amount of water vapor present in the air", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as humid, humidify, and humidor. Its semantic neighborhood includes moisture, dampness, mugginess, and wetness, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Latin humiditas and Latin umēre.