Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
gĕnĭcŭlum, i, n. dim. [genu], a little knee, a knee.
gĕnĭcŭlus, i, m. dim. [genu, a little knee, transf.], in arch., an angular bend where two pipes are joined together, a knee, Vitr. 8, 7.