'Particle physics' definitions:

Definition of 'particle physics'

noun

The branch of physics that studies subatomic particles and their interactions [syn: particle physics, high-energy physics, high energy physics]

From: GCIDE

Particle physics \Par"ti*cle phys`ics\, n. That branch of physics which investigates the nature of matter, and in particular the properties and behavior of the elementary particles (fundamental particles), of which matter is composed. Included in this field is the more specialized branch of high-energy physics. [PJC]