Hypocorism - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Hypocorism
"A hypocorism, or hypochorisma (noun): hypocoristic (adj.) (from Greek ὑποκορίζεσθαι hypokorizesthai, "to use child-talk"[1]) is a lesser form of the given name used in more intimate situations as a nickname, term of endearment, or pet name"