Serous \Se"rous\, a. [Cf. F. s['e]reux. See Serum.]

(Physiol.)
   (a) Thin; watery; like serum; as the serous fluids.
   (b) Of or pertaining to serum; as, the serous glands, membranes, layers. See Serum.

Serous membrane. (Anat.) See under Membrane.

Source: Webster's Revised Unabridged Dictionary (1913)