sag / sag/ • v. (sagged, sag·ging) [intr.] sink or subside gradually under weight or pressure or through lack of strength: he closed his eyes and sagged against the wall. ∎  hang down loosely or unevenly: stockings that sagged at the knees. ∎  have a downward bulge or curve: the bed sagged in the middle. ∎ fig. decline to a lower level, usually temporarily: exports are forging ahead while home sales sag.• n. a downward curve or bulge in a structure caused by weakness or excessive weight or pressure: a sag in the middle necessitated a third set of wheels. ∎  Geom. the amount of this, measured as the perpendicular distance from the middle of the curve to the straight line between the two supporting points. ∎ fig. a decline, esp. a temporary one.DERIVATIVES: sag·gy adj.

sag subside XV; hang loose XVI; (naut.) drift XVII. Corr. in form to Norw. dial. sagga walk slowly and heavily, in sense to MLG. sacken, Du. zakken, Norw. dial. sakka subside, Da. sakke lag behind, drop astern; perh. ult. of W. Scand. orig. and adopted in Du., LG. and Eng. first in nautical use.
Hence sb. movement to leeward XVI; subsidence XIX.

sag. To bend or curve downwards in the middle, from pressure or an object's own weight, e.g. festoon or swag.

SAG (USA) Screen Actors' Guild