Where does “dadless” come from?

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

Ancestry of “dadless”, step by step

dadless 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 dad

StepLanguageWordMeaning
1EnglishdadA father, a male parent; Synonyms: dada, daddy,...
2EnglishDade—
Every word from Proto-Germanic *laus →Every word from Old English lēas →Every word from Middle English les →