enormous
Extremely, impressively large in size, amount, or importance.
Enormous means extremely large in size, amount, or degree. When something is enormous, it's so big that it makes you stop and notice. A blue whale is enormous, stretching as long as three school buses parked end to end. The Grand Canyon is enormous, so vast that you could fit several cities inside it.
The word goes beyond just “big.” An elephant is big, but a full-grown mammoth was enormous. A regular homework assignment might take thirty minutes, but an enormous research project could take weeks. When scientists talk about the enormous distance between Earth and the nearest star beyond our sun (over 24 trillion miles), they're capturing how almost incomprehensibly huge that measurement is.
You can use enormous for things you can't even see or touch. Someone might face an enormous challenge, like learning a new language. A discovery might have enormous importance, changing how we understand the world. The word carries a sense of awe or significance: enormous things command attention and respect simply by their scale.