The term 'loses vigor' can be summarized by two crossword solutions: WILTS (5 letters) and sags (4 letters). Wilting is a process in which plants lose their turgidity, or firmness, due to lack of water. This causes the leaves and stems to droop and become limp. Sagging is a similar process in which something loses its shape or strength due to lack of support. This can be seen in fabrics such as clothing or furniture that has lost its stiffness over time. Both of these terms can be used to describe the loss of vigor in an object or organism.