Physics. a concentrated stream of particles, as electrons, neutrons, or protons, generated for studying particle interactions, nuclear structure, crystal structure, etc.
Military. a high-energy stream of such particles for use as a weapon or for antimissile defense.
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a stream of energized particles produced by a particle accelerator
such a stream emitted by a particle beam weapon
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012