Meaning

noun the 3rd letter of the Greek alphabet

noun a unit of magnetic field strength equal to one-hundred-thousandth of an oersted

noun Portuguese navigator who led an expedition around the Cape of Good Hope in 1497; he sighted and named Natal on Christmas Day before crossing the Indian Ocean (1469-1524)

originLearned borrowing from Ancient Greek γάμμα (gámma). Doublet of gimel.

Etymology from Wiktionary, CC BY-SA 3.0