Templum

Temple of Hercules Victor in the Forum Boarium in Rome
Monopteros round temple of Hercules Victor in the Forum Boarium in Rome. CC Flickr User Northfielder

Definition: Templum is the Latin word from which we get the English "temple". While there is much equivalence, the Latin templum referred not so much to a building type as to an area that was marked out for religious purposes, a sacred place. A templum was the place the auspices could be taken and it was the job of the auspices-takers, the augurs, to mark out the templum. A templum could also be the sacred building with which we are familiar -- marked out as special; however, if it had not been sanctioned by the gods via the augurs, it was not a templum, but an aedes sacra.

The plural of templum is templa.

Source:

Lacus Curtius - Templum Entry from William Smith's A Dictionary of Greek and Roman Antiquities (1875).