Why is the ninth month called September?
"reward, recompense" (now only poetic), late 14c., from Old French guerdon, guerredon "reward, recompense, payment," from Medieval Latin widerdonum, from Old High German widarlon "recompense;" cf. Old English wiðerlean "requital, compensation," from wiðer "again" (see with) + lean "payment." Form influenced in Medieval Latin by Latin donum "gift." Cf. Spanish galardon, Italian guiderone.