Literally thousands of elementary particles have been discovered over the last 50 years, their properties measured, relationships systematized, and existence and behavior explained in a myriad of cleverly constructed theories. As the field has grown so impressively, so has its jargon. This unique handbook contains, in dictionary form, terms of interest in particle physics clearly defined and with relevant technical and mathematics details. It covers the experimental and theoretical techniques of particle physics along with terms from the closely related fields of astrophysics and cosmology. Designed primarily for non-specialists, it contains numerous figures and an extensive bibliography.