1. Small enclosed space or chapel in Antique Rome where the household deities (Lares and Penates) were venerated, often treated as an aedicule, also called lararium.
2. Chantry-, mortuary-, or any other small chapel in a church defined by a screen.
3. Unroofed enclosed space associated with an Ancient Egyptian temple, or found in Roman architecture in connection with religious rites.
"sacellum." A Dictionary of Architecture and Landscape Architecture. . Encyclopedia.com. (August 21, 2018). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/sacellum
"sacellum." A Dictionary of Architecture and Landscape Architecture. . Retrieved August 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/sacellum