Donor

n. giver, contributor, one who donates

A donor in general is a person that donates something voluntarily. Usually used to represent a form of pure altruism but sometimes used when the payment for a service is recognised by all parties as representing less than the value of the donation and that the motivation is altruistic. Often the word is used as a short for:Blood donorElectron donor — (by analogy) a technical term in chemistry and  semiconductor physics (see also the next entry)Acceptor (semiconductors)Organ donorSperm donorCharitable donorIn literature:Donor (fairy tale) is a stock character of fairy tales
See more at Wikipedia.org...

Noun
1. person who makes a gift of property
(synonym) giver, presenter
(hypernym) benefactor, helper
(hyponym) abnegator
2. (medicine) someone who gives blood or tissue or an organ to be used in another person (the host)
(hypernym) benefactor, helper
(hyponym) blood donor
(classification) medicine, medical specialty

n. donor funds, money that has been contributed by donors

(n.)
One who grants an estate; in later use, one who confers a power; -- the opposite of donee.
  

(n.)
One who gives or bestows; one who confers anything gratuitously; a benefactor.