n. The third letter (Γ, γ = Eng. G) of the Greek alphabet. [ 1913 Webster ]
n. A cross formed of four capital gammas, formerly used as a mysterious ornament on ecclesiastical vestments, etc. See Fylfot. [ 1913 Webster ]
. n. (Physics) A very penetrating electromagnetic ray not appreciably deflected by a magnetic or electric field, emitted by radioactive substances.