inexorable
Impossible to stop or change, no matter what happens.
Inexorable means impossible to stop, prevent, or change. When something is inexorable, it keeps moving forward no matter what anyone does, like a massive boulder rolling down a mountain or the steady march of time itself.
You might read about the inexorable advance of a powerful army that nothing could slow down, or the inexorable logic of a mathematical proof that leads inevitably to its conclusion. Winter's arrival feels inexorable: despite our wishes for more warm days, the season changes on schedule every year.
The word carries a sense of both power and inevitability. An inexorable force is relentless and unyielding, refusing to bend or slow down. Think of ocean waves steadily wearing down a cliff over centuries, or the way sunrise follows night no matter what. When a teacher describes someone's inexorable rise to success, they mean that person kept pushing forward through every obstacle with such determination that success became inevitable.
When something is inexorable, begging it to stop or change direction won't help. It will continue on its course.