sb. [L. quid something, pro for, quo (abl. of quid) something.]
1. One thing in place of another; orig. and esp. one medicinal substance used for another, either intentionally, fraudulently, or by mistake.
1565. Calfhill, Answ. Martiall, 32 b. A leude Apoticarie, that vnderstandeth not his bil, but giueth Quid pro Quo.
1601. Holland, Pliny, II. A vj b. Succedan, that drug which may be used for default of another. The Apothecaries call such Quid pro quo.
1654. R. Whitlock, Ζωοτομια, 60. The Apothecaries themselves, both take, and receive (from Herbe-women) Quid pro Quo, one thing for another, many, many Times.
1738. Steward, in Phil. Trans., XL. 449. A Mistake … and a putting of quid pro quo (as ’tis commonly express’d).
1804. Edinb. Rev., III. 416. Referring the proximate cause of this disease to a deficiency of azote is only substituting quid pro quo.
b. The action or fact of using or putting one thing for another; the result of this; a mistake or blunder consisting in such a substitution.
1679. Everard, Discourses, 35. A Capital quid pro quo of Estate of the most part of the Potentates of Europe.
1687. Miége, Grt. Fr. Dict. Quid-pro-quo or mistake, un Qui pro quo.
1727–41. Chambers, Cycl., s.v. Quid. A northern physician, in a printed thesis on quid pro quo’s, owns ingenuously, that they are very frequent.
1824. Lady Morgan, Salvator Rosa, I. v. 263. He … produces the most ludicrous quid pro quo’s by misapplied erudition, witty absurdities, and naïve questions.
1843. Thackeray, Misc. Essays (1885), 44. A laughable quid pro quo … occurred to him in a conversation.
† c. One who assumes a false character. Obs.
1689. Hickeringill, Modest Inquiries, II. 10. Have we not still … some (Quid pro quo’s, amongst us) Papists in Masquerade?
2. One thing (or action) in return or exchange for another; tit for tat.
1591. Shaks., 1 Hen. VI., V. iii. 109. I cry, you mercy, ’tis but Quid for Quo.
1608. Middleton, Mad World, II. iv. 44. Let him trap me in gold, and I’ll lap him in lead; quid pro quo.
1705. Hickeringill, Priest-cr., IV. (1721), 206. Every Church is the Old-Exchange, Spiritual Things in exchange for Carpal Things; Heaven for Earth; Quid pro Quo.
1727. Boyer, Dict. Royal, II. s.v. Quid. To give one Quid-pro-quo (or tit for tat).
1820. Combe, Dr. Syntax, II. xxix. (1869), 167. I shall be able … to bestow What you will find a quid pro quo.
1871. M. Collins, Mrq. & Merch., II. ix. 276. The tradesman gets his quid pro quo.
attrib. 1861. T. A. Trollope, La Beata, II. xvii. 187. A system of conduct based on the theory of a quid-pro-quo purchase.
