Koselleck argued that before roughly 1750 the word "revolution" carried the sense of a turning or a return rather than an irreversible break.

True

True. The older sense is cyclical, a body returning to its starting point, or a state returning to an earlier constitution. The modern sense, of an irreversible movement towards something unprecedented, is one of the conceptual changes Koselleck used to define the Sattelzeit of roughly 1750 to 1850.