Where does “uncle-in-law” come from?

uncle-in-law (English) comes from English Uncle, from Middle English uncle, from Old French uncle, from Latin avunculus, from Proto-Indo-European h₂éwh₂os — maternal grandfather; maternal uncle.

uncle-in-law (English): The husband of one's uncle or aunt (parent's sibling)

Definitions

  1. The husband of one's uncle or aunt (parent's sibling)

Ancestry of “uncle-in-law”, step by step

uncle-in-law traces back through two separate lines of ancestry.

via English Uncle

StepLanguageWordMeaning
1EnglishUncleradiotelephony clear-code word for the letter U
2Middle Englishuncleuncle (brother of one's parents)
3Old FrenchuncleAlternative form of oncle
4Latinavunculusmaternal uncle, mother's brother; mother's...
5Proto-Indo-Europeanh₂éwh₂osmaternal grandfather; maternal uncle

via English in-law

StepLanguageWordMeaning
1Englishin-lawA relative by marriage (or through affinity)
2English-in-lawRelated through marriage
3Englishmother-in-lawThe mother of one's spouse; A mother-in-law...
4Middle Englishmoder in lawemother-in-law
Every word from Proto-Indo-European h₂éwh₂osEvery word from Latin avunculusEvery word from Old French uncle