Final answer:
A scientific theory is a rigorously tested and widely accepted explanation for a range of natural phenomena, supported by a significant body of evidence and repeated verification.
Step-by-step explanation:
The scientific usage of the word theory is best described as a tested and supported explanation that synthesizes a large body of information to account for known facts or phenomena. In science, a theory is not just a guess or hypothesis; it is an explanation that has been substantiated through extensive experimentation and observation. Theories can predict as yet unobserved phenomena, because they are based on a comprehensive set of principles that have been verified multiple times by different researchers. High-profile examples of scientific theories include the theory of evolution, cell theory, and germ theory.