adjective
flaccid
FLAS-id/ˈflæsɪd/
Lacking firmness or strength.
Without enough water, the plant's leaves become flaccid and droop.

Etymology
Latin flaccidus described something flabby, drooping, or weak. The English sense preserves that physical image: something flaccid lacks the firmness needed to hold its shape.
In context
when the guard cells are in the flaccid State stomatal aperture closes during daytime
More examples
- His injured arm hangs flaccid at his side.
- The half-empty balloon feels flaccid in my hand.
- A flaccid argument does little to support her conclusion.
Forms
flaccid
flaccidity noun — The condition of lacking firmness or strength.