Relating to or of the nature of a joint or articulation; having the character of a joint.
From 'articulate' or 'articulus' (joint) plus the suffix '-ary' (relating to). This creates an adjective meaning 'relating to joints or jointedness.'
This is an extremely rare variant of 'articular'—you'd almost never see it in modern English because 'articular' serves the same purpose!
Complete word intelligence in one call. Free tier — 50 lookups/day.