mid-15c., from L. aspersionem (nom. aspersio), from pp. stem of aspergere "to sprinkle on," from ad- "to" + spargere "sprinkle, strew" (see sparse). In theology, the shedding of Christ's blood. Modern sense of "bespattering with slander" first attested 1590s. To cast aspersions was in Fielding (1749).