from The American Heritage® Dictionary of the English Language, 4th Edition
- n. See complement.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A protective substance that exists in the serum or other bodily fluid and is capable of killing microorganisms; complement.
from The Century Dictionary and Cyclopedia
- n. A term originally introduced by Buchner to designate certain substances present in normal blood-serum which are capable of destroying various foreign cellular elements, such as bacteria, red blood-corpnscles, etc.
Greek alexein, to ward off + -in.(American Heritage® Dictionary of the English Language, Fourth Edition)