All 3 Uses

comprehend
in
Rip Van Winkle
(Auto-generated)

During the whole time Rip and his companion had labored on in silence; for though the former marveled greatly, what could be the object of carrying a keg of liquor up this wild mountain, yet there was something strange and incomprehensible about the unknown that inspired awe and checked familiarity.†
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incomprehensible = not understandable

standard prefix: The prefix "in-" in incomprehensible means not and reverses the meaning of comprehensible. This is the same pattern you see in words like invisible, incomplete, and insecure.
Instead of the great tree that used to shelter the quiet little Dutch inn of yore, there now was reared a tall, naked pole, with something on the top that looked like a red nightcap, and from it was fluttering a flag, on which was a singular assemblage of stars and stripes; all this was strange and incomprehensible.†
Rip was equally at a loss to comprehend the question; when a knowing, self-important old gentleman, in a sharp cocked hat, made his way through the crowd, putting them to the right and left with his elbows as he passed, and planting himself before Van Winkle, with one arm akimbo, the other resting on his cane, his keen eyes and sharp hat penetrating, as it were, into his very soul, demanded, in an austere tone, "What brought him to the election with a gun on his shoulder, and a mob at his heels; and whether he meant to breed a riot in the village?"†

comprehend = understand -- especially to understand it completely

Definitions:

(1) (comprehend)
to understand something -- especially to understand it completely
(2) (meaning too rare to warrant focus)
Much more rarely (and more frequently in the past), comprehend can mean to include as part of something broader. That was the first sense of the word listed in Webster's Dictionary of 1828 with this sample sentence: "The empire of Great Britain comprehends England, Scotland and Ireland, with their dependencies."