Where does “underboob” come from?

underboob (English) comes from English boob, from English booby, from English bubby, from English brother, from Middle English brother, from Old English brōþor, from Proto-West Germanic brōþer, from Proto-Germanic brōþēr — brother.

underboob (English): The lower part of a woman's breast, especially...

Definitions

  1. The lower part of a woman's breast, especially...

Ancestry of “underboob”, step by step

underboob traces back through two separate lines of ancestry.

via English boob

StepLanguageWordMeaning
1EnglishboobIdiot, fool; Idiotic, foolish; To behave...
2EnglishboobyA stupid person; Any of various large tropical...
3EnglishbubbyA woman's breast; bub; bubba; Alternative...
4EnglishbrotherSon of the same parents as another person; A male...
5Middle EnglishbrotherA brother or brother-in-law; a male sibling
6Old Englishbrōþorbrother
7Proto-West Germanicbrōþerbrother
8Proto-Germanicbrōþērbrother
9Proto-Indo-Europeanbʰréh₂tērbrother

via English under

StepLanguageWordMeaning
1EnglishunderIn or at a lower level than; As a subject of;...
2Middle Englishunderunder
3Old Englishunderunder, beneath
4Proto-Germanicunderamong, between; under, beneath; under
5Proto-Indo-Europeanh₁entérbetween
6Proto-Indo-Europeanh₁enin; in, inside
Every word from Proto-Indo-European bʰréh₂tēr
underboob — Etymology, Origin & Word History | Etymology Explorer