Apart from the word's many metaphorical uses in non-Hiphop contexts, in Hiphop the word can be used as a noun which refers to a person's respect, power, prestige, etc., or as a verb meaning to go out with someone for their money, not for their looks, personality, etc. (similar in meaning to the verb "to ice", though not necessarily with the connotations of theft)
PART(S) OF SPEECH:
Time to bulid my juice back up-
Props back up, suckers get smacked up
Don't doubt the clout, you know what I'm about
Knocking niggaz off, knocking niggaz out
--Eric B. and Rakim, "Juice (Know The Ledge)"