formidable

FOR-muh-duh-buhl

meaning in plain English

Very big, strong, or powerful, so it makes people feel scared or impressed.

for example

The mountain looked formidable, and the climbers hesitated before trying to reach the summit.

Think of a huge, snarling dog that blocks your path—its size and strength make it a formidable obstacle. You might feel a mix of fear and awe because it seems hard to get past.