noun
Etymology: eta (I)
: an uncharged elementary particle with zero spin that has a mass 1074 times the mass of an electron and that decays rapidly especially into pions — called also eta particle
noun
Etymology: eta (I)
: an uncharged elementary particle with zero spin that has a mass 1074 times the mass of an electron and that decays rapidly especially into pions — called also eta particle
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012