What does "co-uncle" mean?

of a man, an uncle of one's niece or nephew who is not one's brother; a co-brother-in-law as common uncle to the children of two men's married siblings.

What is a synonym for "co-uncle"?

Common synonyms include: co-brother-in-law.

Co-uncle

noun

noun ·Rare ·Advanced level

Definitions

Noun

1
of a man, an uncle of one's niece or nephew who is not one's brother; a co-brother-in-law as common uncle to the children of two men's married siblings.
"Cicero continued however to write anxiously to Atticus, his co-uncle, about the young man's remarkable gifts and unsatisfactory character. [Cicero's younger brother married Atticus's sister, and the couple had a son Quintus; Cicero and Atticus were thus co-uncles to Quintus, the nephew they had in common]"
2
a man's brother, as uncle in common to the children of a third sibling
"My nephew came up for the summer with my brother and co-uncle George."

Synonyms

All synonyms

co-brother-in-law

Example

More examples

"Cicero continued however to write anxiously to Atticus, his co-uncle, about the young man's remarkable gifts and unsatisfactory character. [Cicero's younger brother married Atticus's sister, and the couple had a son Quintus; Cicero and Atticus were thus co-uncles to Quintus, the nephew they had in common]"

Etymology

* co- + uncle

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.