n. pl. se·rums or
se·ra (sîr
ə)
1. The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. Also called blood serum.
2. Blood serum from the tissues of immunized animals, containing antibodies and used to transfer immunity to another individual.
3. Watery fluid from animal tissue, such as that found in edema.
4. Whey.