- theory [thē′ə rē, thir′ē]n.pl. theories [< Fr or LL: Fr théorie < LL theoria < Gr theōria, a looking at, contemplation, speculation, theory < theōrein: see THEOREM]1. Obs. a mental viewing; contemplation2. a speculative idea or plan as to how something might be done3. a systematic statement of principles involved [the theory of equations in mathematics]4. a formulation of apparent relationships or underlying principles of certain observed phenomena which has been verified to some degree5. that branch of an art or science consisting in a knowledge of its principles and methods rather than in its practice; pure, as opposed to applied, science, etc.6. popularly a mere conjecture, or guessSYN.- THEORY, as compared here, implies considerable evidence in support of a formulated general principle explaining the operation of certain phenomena [the theory of evolution ]; HYPOTHESIS implies an inadequacy of evidence in support of an explanation that is tentatively inferred, often as a basis for further experimentation [the nebular hypothesis]; LAW implies an exact formulation of the principle operating in a sequence of events in nature, observed to occur with unvarying uniformity under the same conditions [the law of the conservation of energy ]
English World dictionary. V. Neufeldt. 2014.