A virgule is a forward slash, a punctuation mark that is sometimes used to separate lines of poetry or songs when quoting them in a sentence.
Derived from Latin meaning "a little twig," a virgule has many uses. You can use virgules to separate the month, day, and year in a date, e.g., 12/22/1986. Virgules are often inserted between alternative words, as in "he/she" or "if/when." A virgule is used to mean "per," as in "miles/gallon." Virgules are also used in math, sometimes to indicate division or to separate the parts of a fraction (e.g., ¾). In this quote from an Edgar Allen Poe verse, a virgule separates the lines: "Is all that we see or seem / But a dream within a dream?"