quid (n.1)

"bite-sized piece" (of tobacco, etc.), 1727, dialectal variant of Middle English cudde, from Old English cudu, cwidu (see cud).

"one pound sterling," 1680s, British slang, possibly from quid "that which is, essence," (c. 1600, see quiddity), as used in quid pro quo (q.v.), or directly from Latin quid "what, something, anything." Compare French quibus, noted in Barrêre's dictionary of French argot (1889) for "money, cash," said to be short for quibus fiunt omnia.