Infirmed is a word that refers to someone who is weak or ill. It does have antonyms, many of which are words that suggest strength and health. Some words that are antonyms for infirmed are sturdy, robust, hale, healthy, able-bodied, and sound. Each of these words suggests that a person is not only free of illness but is also strong and capable of doing physical activities. They are words that we might use to describe someone who is in good health and able to fend for themselves. When looking for antonyms for infirmed, it is helpful to think about the opposite qualities of the word and what they imply about a person's physical state.