Virgule

And here I've been calling it a slash:

virgule

\VUR-gyool\

noun 1. a short oblique stroke (/) between two words indicating that whichever is appropriate may be chosen to complete the sense of the text in which they occur: The defendant and his/her attorney must appear in court. 2. a dividing line, as in dates, fractions, a run-in passage of poetry to show verse division, etc.: 3/21/27; “Sweetest love, I do not go/For weariness of thee.” (John Donne)