@Intrepid,
Brandon is correct.Intrepid's definition is irrelevant crap and isnt worth any consideration to science(unless youre a Creationist who doesnt want to accept the definitions that science had adopted for "Theory").The "speculation" aspect of the word is the definition included in a standard English Dictionary and doesnt even pwertain to science.
AGI's definition is accurate and quite symmetrical.
Theory--An explanatory system of propositions, general principles or laws, inferred from the phenomena and linking known facts and observations:A theory is held to be true until contradicted or amended by new facts or observations. Example: Quantum Theory, Evolution,Plate Tectonics,Magnetism"
from, the AGI Glossary of Geology, (ed V) 2005.