Some think this British slang word for a pound sterling comes from the Latin for "what"
The word Quid was also 
used... [DOC] [TLE] Quid | Define Quid at Dictionary.com [PAR] Quid definition, a portion of something, especially tobacco, that is to be chewed 
but ... 1555-65; Latin quid pr qu literally, something for something; see what, 
pro1 ... "one pound sterling," 1680s, British slang, possibly from quid "that which 
is,... [DOC] [TLE] quid (n.1) - Online Etymology Dictionary [PAR] "one pound sterling," 1680s, British slang, possibly from quid "that which is, ... 
used in quid pro quo (q.v.