1. a vaulted room or chamber beneath the main floor of a church or other building
Usage: architecture

Examples

• The medieval cathedral’s undercroft housed ancient tombs and religious artifacts.
• Visitors can explore the stone undercroft beneath the abbey.
• The undercroft served as storage space for the monastery above.
• Archaeological excavations revealed a Norman undercroft under the church.
• The vaulted undercroft provided a cool, dry space for keeping supplies.
• Restoration work began on the 12th-century undercroft last spring.