Where does “flappeth” come from?

flappeth (English) comes from English flap, from Middle English flap.

flappeth (English): Third-person singular simple present indicative...

Definitions

  1. Third-person singular simple present indicative...

Ancestry of “flappeth”, step by step

flappeth traces back through two separate lines of ancestry.

via English flap

StepLanguageWordMeaning
1EnglishflapAnything broad and flexible that hangs loose, or...
2Middle Englishflap

via English eth

StepLanguageWordMeaning
1EnglishethA letter introduced into Old English to...
Every word from Middle English flap