The story
- Proto-Indo-European*lewh₁-
- Proto-Indo-European*lewHs-
- Proto-Germanic*leusaną
- Proto-Germanic*lausaz
- English today-less
From Middle English -les, -leas, from Old English -lēas (“-less”) (compare lēas (“devoid of, loose from, false”)), from Proto-West Germanic *-laus, from Proto-Germanic *-lausaz, from *lausaz (“loose”). (Not related to less, which derives from *laisiz, *laisizô.) Cognate with Scots -less, West Frisian -leas, Saterland Frisian -loos, Dutch -loos, Low German -los, German -los, Danish -løs, Swedish -lös, Icelandic -laus. More at loose.
Etymology from Wiktionary, CC BY-SA 4.0.