'aspersorium' originates from Latin, specifically from the verb 'aspergere' (past participle 'aspersus'), where 'aspergere' meant 'to sprinkle' and the suffix '-orium' meant 'place' or 'instrument'.

'aspersorium' passed through Medieval Latin as 'aspersorium' (a term used in church contexts) and was borrowed into English with the same basic form and liturgical meaning.

Initially it meant 'an instrument or place related to sprinkling', and over time it narrowed to refer specifically to the vessel holding holy water used in liturgical sprinkling.