sag (v.)youdaoicibaDictYouDict
late 14c., possibly from a Scandinavian source related to Old Norse sokkva "to sink," or from Middle Low German sacken "to settle, sink" (as dregs in wine), from denasalized derivative of Proto-Germanic base *senkwanan "to sink" (see sink (v.)). A general North Sea Germanic word (compare Dutch zakken, Swedish sacka, Danish sakke). Of body parts from 1560s; of clothes from 1590s. Related: Sagged; sagging.
slouch (n.)youdaoicibaDictYouDict
1510s, "lazy man," variant of slouk (1560s), probably from a Scandinavian source, perhaps Old Norse slokr "lazy fellow," and related to slack (adj.) on the notion of "sagging, drooping." Meaning "stooping of the head and shoulders" first recorded 1725. Slouch hat, made of soft material, first attested 1764.