The word "revolution" comes from the Latin, revoloutio, which means "a cycle", the word revolution still has that meaning as well in English, but it is interesting that it seems the usage of revolution for "toppling of a government" seems to have changed for most languages in Europe around the same time. And yes, that time was of course around the time of the French Revolution. Before that the word had had an extensive use in history to describe any sort of upheaval or determining event, not particularly involving changes of government (this word is still applied that way, for example with regards to the Industrial Revolution and similar concepts).

The usage of "revolution" as a pre-modern concept most likely stems from classical times, where history by many was seen as cyclical.

Political history for example was believed by some, Aristotle, Plato and Polybius, to evolve as a cyclical motion. Aristotle had divided the forms of government into seven types: 1. Monarchy, 2. Kingship, 3. Tyranny, 4. Aristocracy, 5. Oligarchy, 6. Democracy, and 7. Ochlocracy, and the theory was that a society passed through each form of government until eventually reverting back to the early forms. The same was applied to general history, for example that there was different ages, a Golden Age, Silver Age, and so forth, and when each age had passed it reverted back to begin a new cycle of these ages.

This term was then applied by the ancient Roman historians who used the Latin term revolution to describe when an event occurred that caused this historical cycle to move one step, and this usage of the term was applied by later historians as well, since the foundations of medieval and early modern historical thinking was to a large extent based upon Roman (and Greek) thought. By then the cyclical belief of history had been gradually abandonded, eventually in favour of a progressive view, but the term stuck and was applied to any sort of event that was remarkable or out of the ordinary, like the Glorious Revolution in England.

When the French Revolution occurred the term thus had a long and established history and it was naturally applied to this as well, but the events unfolding there was of such a different order of magnitude that the concept of political revolution was introduced even adopted by the participants themselves as a description of a complete upheaval of government and society. During the 19th century it was embraced by socialist thinkers as well, and the modern meaning was cemented.

This seems like more of a linguistics question, so maybe try /r/linguistics.

breecher is right on the origins of the word. A slight correction is needed though. It's not the case that by the time of the Glorious Revolution of 1688 that revolutions were seen as progress and time as being linear. This came a few decades later.

1688 was still seen as a revolution in the old sense of the word because England was supposedly returning to how it had been governed prior to the Norman Conquest. The idea existed that England had an ancient constitution, derived from Anglo-Saxon times, and that all Englishmen had natural rights which were granted to them by this constitution. The monarchs of England were a continuation of the so called Norman Yoke, which denied Englishmen their freedom. By removing Charles II and bringing in William & Mary as monarchs constrained by Parliament, these ancient natural rights of Englishmen were being restored. Thus, nothing new was being created, instead England was 'revolving', within the natural cycles of history, to a system it had had before. This is the idea of revolution as a restoration rather than upheaval.

Obviously this is a load of nonsense. But it was the accepted political thought at the time.

Though written much later, a good summary of this kind of thinking is Edmund Burke's response to the French Revolution http://socserv2.mcmaster.ca/~econ/ugcm/3ll3/burke/revfrance.pdf

You might find Martin Malia's book The History of Revolutions useful for that question. While the book is currently in my basement, the idea was that the transition from "return to a Golden Age" (as /u/breecher wrote) to "violent destitution of the regime" originates in the Glorious Revolution of 1689, which was then the trope namer for the next (American and French) revolutions.

Definitely worth looking at Raymond Williams' treatment in Keywords, which is available as a pdf online for free.