Quiz: Remember the definition of mal de mer?
early 15c., "watery," later "of or pertaining to serum" (16c.), from French séreux (16c.) and directly from Latin serosus, from serum "watery fluid, whey" (see serum). Related: Serosity.
serous se·rous (sēr'əs)adj. Containing, secreting, or resembling serum.