mid-15c., originally in theology, "the shedding of Christ's blood," from Latin aspersionem (nominative aspersio) "a sprinkling," noun of action from past-participle stem of aspergere "to sprinkle on," from ad "to" (see ad-) + spargere "sprinkle, strew" (see sparse). Non-theological sense of "a bespattering with slander, derogatory criticism" is attested from 1590s. To cast aspersions was in Fielding (1749).
