Lacking strength is a condition that can be caused by a variety of factors, including physical or mental illness, age, or injury. The term can be used to describe a person's physical or mental state. In the crossword puzzle, four words were used to describe this condition: INFIRM (6 letters), FEEBLE (6 letters), WEAK (4 letters), ANEMIC (6 letters), and LIMP (4 letters). INFIRM means physically WEAK or frail, FEEBLE means lacking strength or vigor, WEAK means having little physical or mental strength, ANEMIC means lacking vitality or energy, and LIMP means having little or no strength. All of these words can be used to describe someone who is lacking strength.