[opminion]

In philosophy of science, when discussing what makes a good hypothesis, it is used as disprove.

As in: the existence of the Spaghetti Monster cannot be falsified, and thus to believe in it is an act of faith.

http://www.stephenjaygould.org/ctrl/popper_falsification.htm...

[Gormo]

It doesn't mean "to disprove" as much as it means "to posit a condition under which the statement would be disproved". In other words, a falsifiable claim is one that can be empirically tested, not one that's necessarily already been proven false.

[wcarss]

To be disprovable is to be "falsifiable". To disprove, then, is to "falsify".