Where does “underweight” come from?

Underweight comes from Middle English under- combined with weight, tracing through Old English under-, Proto-Germanic under, and ultimately Proto-Indo-European roots weǵʰ-, wekʷ-, and weyk- related to carrying and moving.

underweight (English): Of an inappropriately or unusually low weight;...

Definitions

  1. Of an inappropriately or unusually low weight;...

Ancestry of “underweight”, step by step

StepLanguageWordMeaning
1Englishunder-Beneath, under
2EnglishunderIn or at a lower level than; As a subject of;...
3Middle Englishunderunder
4Old Englishunderunder, beneath
5Proto-Germanicunderamong, between; under, beneath; under
6Proto-Indo-Europeanh₁entérbetween
7Proto-Indo-Europeanh₁enin; in, inside
Every word from Proto-Indo-European h₁en →Every word from Proto-Indo-European h₁entér →Every word from Proto-Germanic under →