An antiquark is a type of subatomic particle that is the antiparticle of a quark. A meson is a type of particle composed of one quark and one antiquark, and it has five letters. An ATOM is the smallest unit of matter that can exist independently, and it has four letters. A gluon is a type of particle that mediates the strong nuclear force between quarks, and it has five letters. A TOP quark is a type of quark with a charge of 2/3, and it has three letters. Finally, a CHARM quark is a type of quark with a charge of 2/3, and it has five letters.