"Quid pro quo" suggests something good in exchange for something good. You could also say "exchange of favors." That's the best substitute I can think of. Just add Latin to the list of languages we've borrowed words and expressions from. In many cases, they are the shortest and best ways to say something. For example, if you're sending a party invitation, and want people to let you know whether they're coming so you will know how much food to get, you use the initialism "RSVP," which stands for the French expression "Répondez s'il vous plaît." Is there anything better than "RSVP?" No. Some other Latin phrases for which I know no good substitute include "prima facie," "ad hoc," "bonafide," "verbatim," "status quo," "vice versa," etc. There's a non-Latin expression, "tit for tat," but it means something different: something bad in retaliation for something bad.

Quid pro quo comes from Latin and means, I think, “this for that.” It’s a really useful phrase. Finding a synonym is hard and really depends on context. Depending on the context: exchange; trade; you scratch my back, I’ll scratch yours (idiom).

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