Where does “pro quo” come from?

pro quo (Ido) comes from Spanish por qué, from Spanish por, from Old Spanish por, from Vulgar Latin por, from Latin prō, from Latin ratus, from Latin rēōr, from Proto-Italic rēōr — to fit, to fix, to put together.

pro quo (Ido): why, for what reason

Definitions

  1. why, for what reason

Ancestry of “pro quo”, step by step

pro quo traces back through 3 separate lines of ancestry.

via Spanish por qué

StepLanguageWordMeaning
1Spanishpor quéwhy, for what reason
2Spanishporby; for; through, out, via
3Old Spanishpor
4Vulgar Latinporfor
5Latinprōfor
6Latinratusconsidered, having been considered; established,...
7Latinrēōrto reckon, calculate
8Proto-Italicrēōrto reckon, to calculate; to think, to deem, to...
9Proto-Indo-Europeanh₂reh₁-to think, reason; to arrange
10Proto-Indo-Europeanh₂er-to fit, to fix, to put together

via French pourquoi

StepLanguageWordMeaning
1Frenchpourquoiwhy
2Middle Frenchparquoywhy
3Old Frenchpor quoiwhy

via Italian perché

StepLanguageWordMeaning
1Italianperchébecause, why; so, so that, in order that; why
Every word from Proto-Indo-European h₂er-