c. 1400, from forward (adv.) + adverbial genitive -s. British English until mid-20c. preserved the distinction between forward and forwards, the latter expressing "a definite direction viewed in contrast with other directions." In American English, however, forward prevails in all senses since Webster (1832) damned forwards as "a corruption."
fortune-teller
forty
forum
forward
forwardness
forwards
fosse
fossil
fossiliferous
fossilization
fossilize