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Well I hope we're not all making up definitions just to make our job easier in science.

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Of course we do. A given system might be completely uncomprehensible when analyzed with one set of otherwise perfectly good concepts but completely obvious in terms of another set of concepts, with subtly different definitions. This is why, for example, there are a bunch of different formulations of classical mechanics in physics (though they are all equally "right") -- setting up new definitions in terms of which to analyze the same physical system can be of enormous value.

In physics, we have gotten so used to the idea that we just assign the new definitions a different word, or append another word to clear up the ambiguity. E.G. "Oh, you're talking about canonical momentum, not linear momentum." And it's often seen as a sign of progress to tease apart two subtly connected but distinct ideas that were assumed to be the same and given the same name before.