All 7 Uses

hypothesis
in
The Three-Body Problem
(Edited)

This was a reference to two hypotheses, both involving the fundamental nature of the laws of the universe.
p. 74.5

hypotheses = ideas or explanations that are seemingly reasonable, but unproven
In the shooter hypothesis, a good marksman shoots at a target, creating a hole every ten centimeters.
p. 74.5

hypothesis = a seemingly reasonable, but unproven, idea or explanation
The farmer hypothesis, on the other hand, has the flavor of a horror story: Every morning on a turkey farm, the farmer comes to feed the turkeys.
p. 74.7
Unconsciously, he had named the two hypotheses that he ought to have avoided.
p. 91.6

hypotheses = ideas or explanations that are seemingly reasonable, but unproven
She was the first to experimentally disprove the hypothetical "law of conservation of parity" and thereby lend support to the work of theoretical physicists Tsung-Dao Lee and Chen-Ning Yang.
p. 115.9

hypothetical = based on a seemingly reasonable, but unproven, explanation of known facts
According to your hypothesis, there should be another observable situation: The sun must get smaller than it usually appears but bigger than a flying star, and gradually shrink into a flying star as it moves farther away.
p. 184.9

hypothesis = theory
But there was a more direct way to prove the hypothesis: Red Coast itself could transmit radio waves directly at the sun at a power level exceeding the threshold value.
p. 263.6 *

hypothesis = a seemingly reasonable, but unproven, idea or explanation

Definitions:

(1) (hypothesis as in: a study to test her hypothesis)
a seemingly reasonable, but unproven idea or explanation based upon known facts

In casual conversation, theory is a synonym for hypothesis, but a scientist would say that a hypothesis needs to pass rigorous tests before it could be accepted as a theory.
(2) (hypothesis as in: assume as a working hypothesis)
something that may or may not be true, but is temporarily treated as true to advance a discussion or to further investigation

This sense of hypothesis is typically seen in the form, hypothetical, or hypothetically.
(3) (meaning too rare to warrant focus)