Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sincĭpĭtāmentum, i, n. [sinciput], = ἡμικεφάλαιον, a half-head: sincipitamenta porcina, Plaut. Men. 1, 3, 28 Ritschl, Brix.