- A back door; a postern.
- the word employed by Vitruvius, and adopted from him in English, the available vestibule of an old temple into the rear associated with cella, corresponding to the pronaos in front of the temple.
- Eccles., a reredos.
- [pl. postica (-kä).] In Rauff's terminology of sponge morphology, the cloacal openings associated with the exhalant canals or aporrhysa.