digamma
noun
di·gam·ma
dīˈgamə,
ˈdīˌg-
1
: a letter of the original Greek alphabet representing a sound approximately that of English w which early fell into disuse except in writing the western dialects and in numerical notation where it represented the number 6
called also vau
—symbol F, ϝ2
: the sound represented by the letter ϝ
Word History
Etymology
Latin, from Greek, from di- + gamma; from its resemblance to two capital gammas placed on top of each other