quarkonium

[ kwawr-koh-nee-uh m, kwahr- ]
/ kwɔrˈkoʊ ni əm, kwɑr- /

noun Physics.

a meson composed of a quark and an antiquark of the same flavor.

Origin of quarkonium

1975–80; quark + -on1 + -ium, on the model of positronium and similarly named particles