Yes, yo is a Scrabble word!

YO

(noun) Definition: A slang word of greeting, or a term used to get the attention of another.

Popularized by the character Rocky ("Yo, Adrian!" "Yo, Pauley!") in more than four decades of boxing movies, YO is best spoken in a street-slang sort of way (see below).

According to an intriguing 1990s letter to the editor published in The New York Times, YO emerged as part of America’s street slang during the 1930s in Philadelphia (not New York, as many people seem to think). During the early part of the 20th century, South Philadelphia became home to many immigrants from southern Italy. In Neapolitan dialect, the word "guaglione" means "young man" — a word that, in the street slang, was shortened to "gual-yo." This led to the popular greeting among Italian-American men, "Hey, gual-yo!" (pronounced "wal-yo"), which was soon shortened to a simple "Yo!"

In mainstream culture, YO became popular during World War II, when it was commonly used as a response during roll call.

Ways to use YO in a sentence:

• "Yo, what’s up?"
• "Yo, what you doin’?"
• "Yo, did you get that money you owe me?"