Crypt is also a commonly used name of water trumpets, aquatic plants.

In medieval terms, a crypt (from the Latin crypta and the Greek kryptē) is a stone chamber or vault, usually beneath the floor of a church, usually containing tombs of important people such as saints or saints' relics. Typically below ground, churches were occasionally raised above ground level to accomodate a crypt at the ground level, such as St. Michael's Church in Hildesheim, Germany. Crypts are typically found below the apse such as at Saint-Germain en Auxerre , but occasionaly found beneath church wings and naves. First known in the early Christian period, in particular North Africa at Orleansville and Djemila in Algeria, and Byzantium at Saint John Studio in Constantinople. Crypts are most common in the early medieval West, for example in Burgundy at Dijon and Tournus . After the 10th century the need for crypts faded, when Church officials permitted relics to be held in the main level of the church. By the Gothic period crypts were rarely built.

In modern terms a crypt is a stone chamber or vault used to store the deceased. Crypts are usually found in cemeteries and in religious buildings such as cathedrals but are also occasionally found on personal estates. Wealthy or prestigious families will often have a "family crypt" in which all members of the family are stored. Many royal families, for example, have vast crypts containing the bodies of dozens of former royals. In some localities an above ground crypt is more commonly called a mausoleum, which also refers to any elaborate building intended as a burial place, for one or any number of people.