). Any long, narrow vault, either dark or dimly
lighted. It is used in three specific senses:
A tunnel for draining purposes.
A dark vaulted passage in any building, as under the cavea
in the amphitheatre or behind the scena
of a theatre.
A covered corridor above ground, dimly lighted in summer for the sake of coolness, and very
commonly attached to the sides of an open colonnade (porticus
). This was
probably the species of crypta known as cryptoporticus.