The Collaborative International Dictionary
Articulus
Articulus \Ar*tic"u*lus\n.; pl. Articuli. [L. See Article.] (Zo["o]l.) A joint of the cirri of the Crinoidea; a joint or segment of an arthropod appendage.
Wiktionary
articulus
n. (context zoology English) A joint of the cirri of the Crinoidea; a joint or segment of an arthropod appendage.