third letter of the Greek alphabet, c. 1400, from Greek gamma, from Phoenician gimel, said to mean literally "camel" (see camel) and to be so called for a fancied resemblance of its shape to some part of a camel. Gamma rays (1903) originally were thought to be a third type of radiation, but later were found to be very short X-rays.[gamma etymology, gamma origin, 英语词源]