Illustrated Companion to the Latin Dictionary/Clostellum

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

CLOSTEL'LUM. Diminutive of CLOSTRUM. Either the key-hole of a lock; or, perhaps, the box-hasp into which the bolt of a lock shoots; and which would leave a crevice between itself and a door which did not fit close, so that a person might see through it, as mentioned by Petronius, Sat. 140. 11. Compare Senec. Ben. vii. 21.