Boundless means without limits or boundaries. When something is boundless, it seems to go on forever, like the night sky stretching endlessly above you or the ocean extending to the horizon in every direction.

The word often describes things that feel infinite or impossible to measure. A scientist might have boundless curiosity, always asking new questions no matter how many answers she finds. An athlete training for the Olympics might show boundless determination, never giving up despite setbacks and exhaustion. A storyteller's imagination might be boundless, creating world after world without ever running out of ideas.

Boundless means so vast that you can't see where it ends. People sometimes describe the universe as boundless: no matter how far you travel, there's always more space beyond. A young child's energy can seem boundless to tired parents, as if the kid could run and play forever without stopping.

When you encounter something truly boundless, you're facing something that refuses to be contained or measured, something that just keeps going and going.