Specula | Webster's Dictionary of the English Language

specula
spĕcŭla, ae, f. [specio]. I A high place from which to look out, a look-out , watch-tower : specu...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
specula
specula (1) ae, f SPEC-, a look-out, watchtower : ignis e speculā sublatus: dat signum speculā ab ...

An Elementary Latin Dictionary