'asperges' originates from Latin, specifically the word 'aspergere', where 'as-' (variant of ad-) meant 'to' or 'toward' and 'spargere' meant 'to scatter' or 'to sprinkle'.

'asperges' appears in Ecclesiastical/Medieval Latin as the second-person singular present form (and in the antiphon 'Asperges me') and passed into English usage from Medieval/Ecclesiastical Latin as the name of the sprinkling rite.

Initially it was a verb form meaning 'you sprinkle' (or an imperative 'sprinkle'), but over time it came to be used as a noun referring to the ceremony or the antiphon itself.