Articulus

·noun A joint of the cirri of the Crinoidea; a joint or segment of an arthropod appendage.

articulus
artĭcŭlus, i, m. dim. [2. artus], I a small member connecting various parts of the body , a joint ,...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
articulus
articulus ī, m dim.2 artus. a joint, knuckle : crura sine articulis, Cs.: quo iungitur capiti cerv...

An Elementary Latin Dictionary