Quid n. : A portion suitable to be chewed; a cud; as, a quid of tobacco.

Quid v. t. : To drop from the mouth, as food when partially chewed; -- said of horses.

Example:
Why do the British call a pound as in pound sterling a Quid as well?

Taxonomy
free encyclopedia, Irish slang, monetary currency, food labelling, Latin phrase, search, free dictionary, meanings, British slang, Australian slang, abbreviation, tertium quid, third party, Madison, the Democratic, prototype, possible future, disambiguation pages.

Defination from the web:
... Quid pro quo, the Latin phrase meaning this for that. This disambiguation page lists articles associated with the same title. ...