When something is incomprehensible, you cannot understand it, no matter how hard you try. The instructions might be so confusing, the explanation so unclear, or the idea so complex that it simply doesn't make sense to you.

Imagine opening a book written entirely in ancient Greek when you only speak English: the text would be incomprehensible. Or picture a brilliant physicist explaining quantum mechanics using technical terms you've never heard before. Her explanation might be perfectly clear to other scientists, but incomprehensible to someone without that background.

Something incomprehensible is truly beyond your grasp at that moment, going past difficult or challenging to feeling completely impossible to understand. A younger sibling's scribbled drawing might seem incomprehensible until they explain it's supposed to be your family dog.

Notice that what's incomprehensible to one person might be perfectly clear to another. Advanced calculus seems incomprehensible to most fourth graders, but it makes complete sense to mathematicians. That's why good teachers work hard to make complicated subjects comprehensible by breaking them down, using examples, and explaining terms clearly.