Lucus

In ancient Roman religion, a lucus ([ˈɫ̪uː.kʊs], plural lucī) is a sacred grove.

Lucus was one of four Latin words meaning in general "forest, woodland, grove" (along with nemus, silva, and saltus), but unlike the others it was primarily used as a religious designation, meaning "sacred grove". Servius defines the lucus as "a large number of trees with a religious significance," as distinguished from the silva, a natural forest, and a nemus, an arboretum that is not consecrated. A saltus usually implied a wilderness area with varied topographical features.

A lucus was a cultivated place, more like a wooded park than a forest, and might contain an aedes, a building that housed the image of a god, or other landscaped features that facilitated or gave rise to ritual. It has been conjectured, for instance, that the Lupercal, referred to as a "cave," was a small lucus with an artificial grotto, since archaeology has uncovered no natural cave in the area.

Apuleius records that "when pious travelers happen to pass by a sacred grove (lucus) or a cult place on their way, they are used to make a vow (votum), or a fruit offering, or to sit down for a while."