Quid

[kwid] /kwɪd/

noun
1.
a portion of something, especially tobacco, that is to be chewed but not swallowed.
[kwid] /kwɪd/
noun, plural quid.
1.
British Informal. one pound sterling.
[kwid proh kwoh] /ˈkwɪd proʊ ˈkwoʊ/
noun, plural quid pro quos, quids pro quo for 2.
1.
(italics) Latin. one thing in return for another.
2.
something that is given or taken in return for something else; substitute.
/kwɪd/
noun
1.
a piece of tobacco, suitable for chewing
/kwɪd/
noun (pl) quid
1.
(Brit, slang) one pound sterling
2.
(Brit, slang) quids in, in a very favourable or advantageous position
3.
(Austral & NZ, slang) not the full quid, mentally subnormal
/ˈkwɪd prəʊ ˈkwəʊ/
noun (pl) quid pro quos
1.
a reciprocal exchange
2.
something given in compensation, esp an advantage or object given in exchange for another
n.

“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.” Cf. French quibus, noted in Barrêre’s dictionary of French argot (1889) for “money, cash,” said to be short for quibus fiunt omnia.

1560s, from Latin, literally “something for something, one thing for another,” from nominative and ablative neuter singulars of relative pronoun qui “who” (see who) + pro “for” (see pro-) + quo, ablative of quid.
quid pro quo [(kwid proh kwoh)]

A fair exchange; the phrase is most frequently used in diplomacy: “The Chinese may make some concessions on trade, but they will no doubt demand a quid pro quo, so we must be prepared to make concessions too.” From Latin, meaning “something for something.”
An equal exchange or substitution, as in I think it should be quid pro quo—you mow the lawn and I’ll take you to the movies. This Latin expression, meaning “something for something,” has been used in English since the late 1500s.