An Etymological Dictionary of Astronomy and Astrophysics

Any of a group of four short-lived → mesons distinguished by a → quantum number called → strangeness. Also called K meson and denoted K. They are positive, negative, or neutral and have a mass of about 495 MeV/c (about 970 times that of an → electron).

See also: Kaon, from ka (for the letter K) + (mes)on, → meson.