Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pro-lībo, āre, v. a., to pour out, offer as a libation to the gods (Plinian): vina diis, Plin. 14, 18, 22, § 117; 14, 19, 23, § 119; 28, 4, 11, § 46.
Impers. pass.: fictilibus prolibatur simpuviis, Plin. 35, 12, 46, § 158.