Where does “peabrain” come from?

peabrain (English) comes from English pea, from English pease, from Middle English pese, from Old English pise, from Late Latin pisa, from Latin pīsum, from Ancient Greek πίσον, from Ancient Greek πίσος — pea, pease, seed of "Pisum sativum".

peabrain (English): a stupid or clumsy person; a cretin; stupid,...

Definitions

  1. a stupid or clumsy person; a cretin; stupid,...

Ancestry of “peabrain”, step by step

peabrain traces back through two separate lines of ancestry.

via English pea

StepLanguageWordMeaning
1EnglishpeaAny of certain plants of the family Fabaceae: Pisum sativum and others
2EnglishpeaseTo make peace between (conflicting people, states etc.); to reconcile
3Middle EnglishpeseA pea; The leguminous plant Pisum sativum;...
4Old Englishpisepea
5Late Latinpisanominative plural of pisum; accusative plural of...
6Latinpīsumpea, pease
7Ancient GreekπίσονQuoted by comic poet Alexis; pea, pease, seed of...
8Ancient Greekπίσοςpea, pease, seed of "Pisum sativum"

via English brain

StepLanguageWordMeaning
1EnglishbrainThe control center of the central nervous system...
2Middle EnglishbraynThe brain or cerebrum; the organ of thought;...
3Old Englishbræġnbrain
4Proto-West Germanic*bragnbrain
5Proto-Germanicbragnąbrain
6Proto-Indo-Europeanmregʰnomskull, brain
7Proto-Indo-Europeanmen-to think, mind; spiritual activity; to stay,...
Every word from Ancient Greek πίσοςEvery word from Ancient Greek πίσονEvery word from Latin pīsum