Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. lustrāmentum, i, n. [lustro], a means of purification, Arn. in Psa. 118, Serm. 8.
2. lustrāmentum, i, n. [lustror], an incentive to lust: si quis lustramenti causā dederit cantharides, Dig. 48, 8, 3.