Final answer:
Multi-axial refers to a type of joint that permits movement in multiple planes, including flexion/extension and abduction/adduction, and is associated with complex motion like circumduction and rotation.
Step-by-step explanation:
The term multi-axial as it relates to the CCI refers to the type of movement that occurs at a multiaxial joint. A multiaxial joint is one that allows for several directions of movement, including flexion/extension, abduction/adduction, circumduction, and medial/lateral rotation. Essentially, these joints are capable of motion in multiple planes and can execute a wider range of movements compared to uniaxial or biaxial joints, which are limited to one or two planes respectively.