To fold or hang downward: "Their mouth drooped unfortunately, pulled straight down, definitely, because of the plump weight of their jowls” ( Gore Vidal).
To flex or droop gradually: flowers drooping into the midday heat.
To sag in dejection or fatigue: drooped from lack of sleep.
To hang bending downward; to sink or hang down, as an animal, plant, etc., from physical inability or fatigue, want of nourishment, and/or want.
to develop weak or faint with disappointment, grief, or like causes; to-be dispirited or depressed; to languish.
To continue downward, or toward a detailed; to decrease.
How would you define droop?