droop

Short definition from Wiktionary

Verb

1. 1
   To hang downward; to sag.
2. 2
   To slowly become limp; to bend gradually.
3. 3
   To lose all energy, enthusiasm or happiness; to flag.
4. 4
   To allow to droop or sink.
5. 5
   To proceed downward, or toward a close; to decline.

Noun

1. 1
   Something which is limp or sagging.
2. 2
   A condition or posture of drooping.
3. 3
   A hinged portion of the leading edge of an aeroplane's wing, which swivels downward to increase lift during takeoff and landing.

Adjective

1. 1
   Drooping; adroop.