1. a member of a medieval military and religious order, especially the Knights Hospitaller, founded to care for pilgrims and the sick
Usage: historical; often capitalized when referring to the specific order
2. a person in charge of a hospital or hospice; a hospital administrator or keeper
Usage: archaic; rare in modern usage

Examples

• The Hospitallers were known for their naval power in the Mediterranean during the Middle Ages.
• A hospitaller of the order took vows to serve both God and the sick.
• The Knights Hospitaller established hospitals throughout the Holy Land.
• Medieval hospitallers provided shelter and medical care to Christian pilgrims.
• The hospitaller order eventually relocated to Malta after losing Rhodes.