Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-nĕo, nēvi, nētum, 2, v. a., to spin out, spin to an end, poet. of the Fates: cum mihi supremos Lachesis perneverit annos, Mart. 1, 89, 9; Sid. Carm. 15, 167.