'armarium' originates from Latin, specifically the word 'armarium', where 'arma' meant 'arms, weapons' and the suffix '-arium' meant 'place for'.

'armarium' passed from Classical Latin into Medieval Latin with the sense of a storage place; it appeared in Middle English forms such as 'armarie' and later continued in scholarly and ecclesiastical English as 'armarium'.

Initially, it meant 'a chest or container for arms'; over time it evolved into the modern specialized senses of 'cupboard, niche, or bookcase' used especially in ecclesiastical and monastic contexts.