Virgule

The virgule (/), is known by many names, including diagonal, solidus, oblique, slant, slash, forward slash, and slash mark. The virgule is used to represent a word that is not written out or to separate or set off certain adjacent elements of text.

A virgule most commonly signifies alternatives. In certain contexts it represents the word or.

Examples:

he/she
his/her
oral/written tests
and/or
alumni/ae

A virgule represents the word per or to when used with units of measure or when used to indicate the terms of a ratio.

Examples:

40,000 tons/year
14 gm/100 cc
9 ft./sec.
a 50/50 split

A virgule replaces the word and in some compound terms.

Examples:

in the May/June issue
1973/74
parent/child problems

A virgule punctuates some abbreviations and in lieu of a period.

Examples:

c/o
w/
w/o
S/Sgt
d/b/a




Source: Grammar Done Right!