1756, "pertaining to the synovia," albuminous fluid secreted by certain glands, from Modern Latin sinovia (16c.), probably coined by Paracelsus and apparently an invented word. With -al (1).
Entries linking to synovial
-al 1
suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).