biarticulate
/ˌbaɪˈɑːrtɪkjʊleɪt/Definitions
1. adjective
Having two joints or articulations.
“The biarticulate knee of the jumping spider enables it to leap with great precision.”
2. noun
A joint or articulation that is divided into two parts.
“The biarticulate joint of the dinosaur’s leg was a crucial factor in its mobility.”