Answer:
A lubricating fluid that reduces friction between the bones is found in synovial joints.
Step-by-step explanation:
Synovial fluid is a viscous solution found in the cavities of synovial joints. The principal role of synovial fluid is to reduce friction between the articular cartilages of synovial joints during movement.
Further information can be found in ...
NCBI's article Hyaluronan and synovial joint: function, distribution and healing