Where does “flapless” come from?

flapless (English) comes from English less, from Middle English les, from Old English lēas, from Proto-Germanic *laus.

flapless (English): Without a flap or flaps

Definitions

  1. Without a flap or flaps

Ancestry of “flapless”, step by step

flapless traces back through two separate lines of ancestry.

via English less

StepLanguageWordMeaning
1EnglishlessTo a smaller extent or degree; comparative form...
2Middle Englishlesfalse; lying; deceptive; falsehood; a lie
3Old Englishlēasfalse, lax; false, void, loose; devoid of, loose...
4Proto-Germanic*laus

via English flap

StepLanguageWordMeaning
1EnglishflapAnything broad and flexible that hangs loose, or...
2Middle Englishflap
Every word from Proto-Germanic *laus