a stone chamber wholly or partly underground, beneath the floor of a church or other building and usually containing coffins, sarcophagi, or religious artifacts;
e.g. The skeletons shared their crypt with ancient relics.
(noun)
a narrow but deep tubular gland, pit, recess, or invagination into a larger structure;
e.g. Intestinal glands in the colon are also known as colonic crypts.