synovial
adjective /saɪˈnəʊviəl/, /sɪˈnəʊviəl/
/sɪˈnəʊviəl/
(biology)- (of a part of the body ) having a membrane (= a piece of very thin skin) containing liquid between the bones, which allows the joint to move freelyWord Originmid 18th cent.: from modern Latin synovia, probably formed arbitrarily by Paracelsus (c. 1493-1541), the Swiss physician.