Infirm means physically weak or frail, usually because of old age or illness. When someone is infirm, their body doesn't work as well as it used to: they might struggle to walk long distances, tire easily, or need help with tasks they once handled on their own.

You'll often hear this word describing elderly people whose bodies have grown weaker over time. An infirm grandmother might need a cane to walk or assistance climbing stairs. A previously active grandfather who becomes infirm after a long illness might spend more time resting than he'd like.

The word focuses specifically on physical weakness rather than mental sharpness. An infirm person might still be brilliant, witty, and mentally alert, even though their body has become frail. This matters: someone can be physically infirm while remaining wise, capable of making decisions, and valuable to their family and community.

Infirmary comes from the same root. It's a place where sick or injured people receive medical care, especially in schools or workplaces. The connection makes sense once you know that both words relate to physical weakness or illness.