Points of connection between two elements (6)
I believe the answer is:
joints
'points of connection between two elements' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for joints that I've seen before include "Points of connection between two bones" , "Junctions, unions" , "Structures in body in which bones are fitted together" , "Points of connection between two elements" .)