de Broglie waves (d? ?br???l?) pl n (General Physics) physics the set of waves that represent the behaviour of an elementary particle, or some atoms and molecules, under certain conditions. The de Broglie wavelength, ?, is given by ? = h/mv, where h is the Planck constant, m the mass, and v the velocity of the particle. Also called: matter waves [C20: named after Prince Louis Victor de Broglie (1892?1987), French physicist]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014