droop
noun.
a shape that sags
there was a sag in the chair seat
Synonym: sag
verb.
droop, sink, or settle from or as if from pressure or loss of tautness
Synonym: flag, sag, swag
verb.
hang loosely or laxly
His tongue lolled
Synonym: loll
verb.
become limp
The flowers wilted
Synonym: wilt