A blue gaseous allotrope of oxygen, O3, formed naturally from diatomic oxygen by electric discharge or exposure to ultraviolet radiation. It is an unstable, powerfully bleaching, poisonous oxidizing agent with a pungent, irritating odor, used to deodorize air, purify water, treat industrial wastes and as a bleach.
Co-movement A key feature of the Burns and Mitchell economic was to focus on the amount of cyclical co-movement or coherence among a large number of economic variables. This co-movement is the prime characteristic of their definition of the business cycle: "...a cycle consists of expansions occurring at about the same time in many economic activities, followed by similarly general recessions, contractions, and revivals which merge into the expansion phase of the next cycle....in duration business cycles vary from more than one year to ten or twelve years..."