The word comprehension means understanding. When you lack comprehension of a difficult word, you will likely need to look up its definition and usage in a cool, down-to-earth online dictionary!
Comprehension actually comes from the Latin term, comprehensionem, which means "a seizing." When you have comprehension of a subject, you have seized information and incorporated it into your own knowledge. Any kind of mental grasping of an idea or a subject is a kind of comprehension. You might attempt comprehension of a curious situation, like the fact that your goofy roommate always manages to date models. Sometimes, such mysteries are beyond comprehension!