A hypothesis or model is called falsifiable if it is possible to conceive of an experimental observation that disproves the idea in question. That is, one of the possible outcomes of the designed experiment must be an answer, that if obtained, would disprove the hypothesis.
To say that a certain hypothesis is falsifiable is to say that there is possible evidence that would not count as consistent with the hypothesis. According to Popper, evidence cannot establish a scientific hypothesis, it can only “falsify” it. A scientific hypothesis is therefore a falsifiable conjecture.