Meaning

noun a shape that sags

verb droop, sink, or settle from or as if from pressure or loss of tautness

verb cause to sag

originFrom earlier sag, sagg, sack, from Middle English saggen, probably from Middle Low German sacken (“to sink, drift”), ultimately of North Germanic/Scandinavian/Old Norse origin, akin to Old Norse søkkva (“to sink”), from a denasalized derivative of Proto-Germanic *sinkwaną (“to sink”). Cognate with Scots seg (“to sink”), Danish sakke (“to lag behind”), Swedish sacka (“to lag”), Icelandic sakka…

Etymology from Wiktionary, CC BY-SA 3.0