Watery (typically serous) fluid produced by a pathological process or condition (as oedema, effusion, hydrocephalus, etc.); accumulation of such…

concrete. Abnormal watery liquid contained within the body or a part of the body. Obsolete.

Watery fluid in an animal body; the serous or watery part of blood or milk, serum; frequently plural in 17–18th centuries = watery humours.

Medicine. A clear liquid believed to be a component of a humour (humour, n. 1a) or other body fluid; esp. plasma and lymph. Now historical and rare.

Any watery fluid of animal origin. Obsolete.

Watery animal fluid, normal or morbid; spec. blood-serum, the greenish yellow liquid which separates from the clot when blood coagulates.