Infirmness is a word that describes the lack of strength or firmness. Its antonyms are the words strength, firmness, robustness, vitality, and resilience. Strength describes the physical ability of something or someone to withstand damage or pressure. Firmness indicates the level of support or stability in something or someone. Robustness refers to the ability to resist disease or illness. Vitality suggests the life force, energy, and vigor of a person or organism. Resilience describes the capacity to recover quickly from difficulties, setbacks, or trauma. Antonyms for infirmness are essential concepts that help us understand the opposite qualities in individuals or things.