Yo

[Tina]

1. A contraction of the possessive prenominal adjective your.
2. An informal address or title to one whose name is not known to another; can be used as an interrogative address.
   3)A declaritive or imperative exclaimation, whether alone or within a sentence.

[Sarah]

Another Way of saying hey or hi

[Tina]

the one word that can be added to almost any sentence and work

[Britney]

a slang way of saying hello, usually friendly and casual

[Donald Trump]

Substitution for Greetings!
Dislexic Rabbi speak
Filler-speech when a need to look gangsta is at hand
Half of a Yo-yo

[Mark Zuckerberg]

A word whos origin is made to be puzzling, but is really made famous by the Movie Rocky and by various rappers. Yo is a word deeply connected in the Philadelphia culture, therefore; no, it is not used only by little black kids or wannabe suburbans like the definitions before it has stated.
A history lesson about the words popular use in Philly from the New York Times:
In the 1930s a large proportion of the residents of South Philadelphia were Italian immigrants, mostly from the Campania region of southern Italy, the principal city of which is Naples.
In the Neapolitan dialect guaglione (pronounced guahl-YO-nay) signified a young man. The chiefly unlettered immigrants shortened that to guahl-YO, which they pronounced whal-YO. That was inevitably further shortened to yo. The common greeting among young Italian-American males was Hey, whal-YO!, and then simply, Yo! And so it remains today.
Sorry for this long post, but I had to handle my business about my city.
And the Yo is the pronounciation of the word youre, is usually spelled yo.

[Sonia]

a word that died a horrible death in 1993 but still manages to haunt us through usage by white kids in nice neighborhoods who by some strange dementia think they are from the projects. you poor unfortunate soul.

[Tanya Shivari]

how rappers/thuggers begin and end every sentence..
used when rappers cant find a word to finish their song..

[Jessica]

Its what un-educated people say most of the time.

[Rihanna]

1)Used to get someones attention
2)Used by white suburan kids to help them think they are cool while they wear throwback sports clothing that is too big for them.
3)A short word for Hi or Hello.

[Zipporah Schumaker]

A greeting, can also mean a Woman friend or [associate] that isnt [intimate] which in plural is [Yos]

[Tanya Shivari]

In the English language, yo has become a common interjection that originated decades ago in the Philadelphia region. It is often interchangeable with the word hey, as in Yo, whats up? or, Yo! Wait for me! While the word can also stand alone as a greeting, like the word hey, it also has a wide range of meanings that depend on the tone, context, and situation in which it is used. (see examples)
In more recent times the word has spread into hip-hop or gangsta culture. A parody of such usage forms the basis for a comic exchange between the animated characters played by Robert DeNiro and [Martin Scorsese] ([Shark Tale], 2004), which can be viewed here (http://yoism.org/index.php?id=[YoST]/).
Members of this later cultural scene may claim its origin as theirs. The words origin, however, clearly predates these recent uses, as is evidenced by the words of [Rocky Balboa] (played by Sylvester Stallone)
Yo, Adrienne, its me, Rocky... Rocky Balboa (Rocky, 1976)
Yo, Adrienne. We did it! Rocky Balboa (Rocky II, 1979)

[Sommer]

[Slang] [for you].

[Tracie Lynn]

[GANGSTA] SLANG
In that case yo is a short form of the [possessive] [pronoun] your.

[Sarah]

A word of [greeting] that sounds [orgasmic] when [Eminem] says it.

[Tariq Zaki]

the guy whos so [gd up] he cant say hi, [hello] or how ya [doin]?

[Lizzy Liz]

Interchangeable with the [words] [huh] or what or [hey]