Monumental describes something impressively large, important, or significant. When architects design a monumental building like the U.S. Capitol or the Great Pyramid of Giza, they create a structure so grand it becomes a landmark people remember for generations. A scientist making a monumental discovery, like figuring out how DNA works, changes entire fields of knowledge.

The word comes from “monument,” those lasting structures we build to commemorate important people or events. This origin gives monumental its sense of being meaningfully big: something worth remembering or celebrating.

You'll encounter monumental describing efforts and challenges too. Cleaning up after a huge storm might be a monumental task, not because it's impossible but because it requires enormous work and determination. Learning to play the piano well takes monumental patience and practice. When someone achieves something monumental, they've accomplished something so substantial that people take notice. It's a step beyond merely large or difficult: it's something that matters, something that stands out like a monument on the horizon.