chaos theory UK /ˌkeɪɒs ˈθɪəɹi/US /ˌkeɪˌɑs ˈθiəɹi/ noun1 •The study of chaos or disorder in systems, specifically iterative non-linear systems in which arbitrarily small variations in initial conditions become magnified over time, and where within apparent randomness there are underlying patterns; (countable) one of such theories. formschaos theories