A small chapel, as a monument within a church(noun)
A shrine open to the sky, sometimes used for sacrificial purposes, or in honor of the divine(noun)
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Use "sacellum" in a sentence
"In that case, the open front and the niche in the back wall could suggest that one is dealing here with a kind of sacellum (or shrine) dedicated to the cult of Marcus Aurelius, to whom the whole complex was dedicated."
"The other appellation "sacellum," applied by Boece to the hermit's chapel, is a better known and more classical word than the capellula of the _Scotichronicon_."
"Cicero himself has left us a complete definition of the word, for he has described "sacellum" as "locus parvus deo sacratus cum ara." ["