In addition, large-scale climate events like El Nino and La Nina redistribute vast water masses among Earth's ocean, atmosphere and land. Scientists care because, to put movements of Earth's crust into proper context, they need a frame of reference to evaluate them against.
Adj. 1. operant-having influence or producing an effect; many emotional determinants at work; an operant conscience. operative-being in force or having or exerting force; operative regulations; the major tendencies operative in the American political system. 1  Facebook.
Full Definition of OPERA. 1. : a drama set to music and made up of vocal pieces with orchestral accompaniment and orchestral overtures and interludes; specifically: grand opera. 2. : the score of a musical drama. 3. : the performance of an opera; also: a house where operas are performed.