theory

noun

1
a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena
a scientific hypothesis that survives experimental testing becomes a scientific theory
he proposed a fresh theory of alkalis that later was accepted in chemical practices
2
a belief that can guide behavior
the architect has a theory that more is less
they killed him on the theory that dead men tell no tales
3
a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena
theories can incorporate facts and laws and tested hypotheses
true in fact and theory

Also useful for “theory”:Unscrambler— Rearrange the letters in “theory”