Meaning

noun a characteristic (habitual or relatively temporary) state of feeling

noun a message whose ingenuity or verbal skill or incongruity has the power to evoke laughter

noun (Middle Ages) one of the four fluids in the body whose balance was believed to determine your emotional and physical state

originFrom Middle English humour, from Old French humor, humour, from Latin hūmor, correctly ūmor (“liquid”), from hūmeō, correctly ūmeō (“to be moist”). The h in these words, which was silent in late Classical Latin, is folk etymological, due to the erroneous association with the word humus (“soil”). The shift in meaning "liquid" > "mood" is attributed to the classical system of physiology, where…

Etymology from Wiktionary, CC BY-SA 3.0