While the Oxford English Dictionary gives you the meaning of the word as well as its origin, the Cambridge Dictionary gives a more practical explanation along with an example of how to use the word in a sentence.

noun. attractiveness, charm, or skill in flirtation that allows one to easily attract romantic or sexual partners: I've lost all my rizz, but I think it's a sign to focus on school.

proper noun. The World Wide Web is a computer system which links documents and pictures into a database that is stored in computers in many different parts of the world and that people everywhere can use.