The Collaborative International Dictionary
Sacella
Sacellum \Sa*cel"lum\, n.; pl. Sacella. [L., dim. of sacrum a sacred place.]
(Rom. Antiq.) An unroofed space consecrated to a divinity.
(Eccl.) A small monumental chapel in a church.
--Shipley.
Wiktionary
sacella
n. (plural of sacellum English)