When musicians collaborate on tracks and instead of saying featuring they'd rather use the short terminology "x". This is traditionally used to represent the group of artists as an equal collaboration; their verses shouldn't be seen as a "feature" but rather the second half of the song. "Featuring" however is traditionally used to indicate another artist's addition to the main artist's song, hence the use of the term featuring. Nowadays the traditional uses for these terminologies are recreational.
Example of "X": Musician 1 x Musician 2 - Song Title
Example of "Featuring": Musician 1 - Song Title (Featuring Musician 2)
Why use boring Latin alphabet to write letter X, when you can use it to solve your math trigonometry homework?
"Xylographic xysts xerox Xaverian xylophones."
To commit murder. Short for execute.
G be skimming.
Then x that mu'afucka, yo.