Serum
/ˈsɪr.əm/noun
The clear watery part of blood that remains after clotting, or a liquid preparation used in medicine or cosmetics.
Did you know?*Serum* entered English through Latin *serum* meaning “whey” or “the clear liquid of milk,” a reminder that the word originally described a pale leftover fluid before it became a medical term.
Etymological Timeline
Proto-Indo-European
PIE
*ser-
“to flow, drip, or ooze”
Latin
Latin
serum
“whey; the clear liquid separated from curds”
Late Latin
Latin
serum sanguinis
“the clear fluid of blood”
18th Century
English
serum
“the watery part of blood or other bodily fluid”
Modern English
English
serum
“the clear liquid portion of blood, especially after clotting; also a medicinal or cosmetic preparation”