The Collaborative International Dictionary of English v.0.48:

Aspergill \As"per*gill\, Aspergillum \As`per*gil"lum\, n. [LL.
   aspergillum, fr. L. aspergere. See Asperse, v. t.]
   1. The brush used in the Roman Catholic church for sprinkling
      holy water on the people. [Also written aspergillus.]
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   2. (Zool.) See Wateringpot shell.
      [1913 Webster]