A1N1T1I1P3A1R1T1I1C3L1E1S1
17 points
ANTIPARTICLES is validvalid
ANTIPARTICLE, [n]
ANTIPARTICLE, the 'pair' of an elementary particle, particle and antiparticle being mutually destructive, having the same mass and spin but having opposite values for their other properties (e.g. charge, baryon number, strangeness) [n]