An infirmary is a facility which cares for people who are sick, injured, or infirm. The capabilities of an infirmary vary: some are set up like hospitals, capable of treating a wide range of conditions, while others provide more simple and basic medical care. When the term “infirmary” is used, most people think of a facility which offers a very simple level of care, like a nurse's office in a school, although some of the most famous hospitals in the world are also known as infirmaries, which can be confusing.

The word is derived from the Latin infirmus, which means “infirm.” Facilities which provide medical care have been available to humans for centuries, although the quality of that care has varied widely. Typically, an infirmary is attached to an institution like a school or prison, providing care for residents and employees of the organization. The availability of on-site care can make a facility safer and it may also appeal to people evaluating the facility's level of care.

When an infirmary is attached to an institution, it typically has a few beds for patients to rest in, along with cabinets of basic medical supplies like bandages, simple medications, and so forth. A nurse practitioner or lay nurse staffs the infirmary, providing simple care to people with very basic medical needs. In the event that more serious care is required, a doctor may be called for, or the patient may be transported elsewhere.

Some people also refer to an infirmary as a dispensary, in a reference to the medications which are handed out by the staff. In some cases, people who attend an institution are required to hand over any prescriptions that they have to ensure that they are not abused. When they need their medications, they go to the infirmary to receive a measured dose from the nurse, who may supervise the administration of the medication to ensure that the patient takes it.

Famous hospitals which are known as infirmaries typically started out as small facilities offering basic care, and some of them are very old. Many such institutions started as simple services offered by concerned doctors or community organizations, and they grew into major medical institutions over time. Some of these infirmaries continue to place a heavy focus on charitable work, since this was their original purpose.