Where does “mushbrain” come from?

mushbrain (English) comes from English MUSH, from English mushroom, from Middle English muscheron, from Anglo-Norman musherum, from Old French moisseron, from Old French mosse, from Frankish mosa, from Proto-Germanic musą — fly, stinging fly, gnat; moist, damp; swamp,...

mushbrain (English): A stupid person

Definitions

  1. A stupid person

Ancestry of “mushbrain”, step by step

mushbrain traces back through two separate lines of ancestry.

via English MUSH

StepLanguageWordMeaning
1EnglishMUSHA form of multi-user dungeon, often used for...
2EnglishmushroomAny of the fleshy fruiting bodies of fungi...
3Middle Englishmuscheronmushroom
4Anglo-Normanmusherum
5Old Frenchmoisseron
6Old Frenchmossemoss
7Frankishmosamoss
8Proto-Germanicmusąmoss, bog
9Proto-Indo-Europeanmūs-fly, stinging fly, gnat; moist, damp; swamp,...

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 Proto-Indo-European mūs-