Droop (verb)

1. To hang downward limply or listlessly.
2. To become weaker or less intense.
3. To sink or bend down, typically from tiredness or lack of vitality.

Origin:

Old english dreopan "to drip, fall in drops," of germanic origin; related to drip.

Examples:

1. The flowers drooped in the heat.
2. His shoulders drooped in defeat.
3. Her head drooped as she fell asleep.