Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
lancĕārĭus, v. lanciarius.
lancĭārĭus (lancĕār-), ĭi, m. [lancea], a lancer (post-class.), Amm. 21, 13, 16; Cassiod. Hist. 6, 35; Vulg. Act. 23, 23.