*digamma*

n. [ Gr. &unr_;; &unr_; = &unr_; twice + ga`mma the letter Γ. So called because it resembled two gammas placed one above the other. ] (Gr. Gram.) A letter (&unr_;, &unr_;) of the Greek alphabet, which early fell into disuse. [ 1913 Webster ]

☞ This form identifies it with the Latin F, though in sound it is said to have been nearer V. It was pronounced, probably, much like the English W.