Both Uses

comprehend
in
The Boy on the Wooden Box
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That our misery, confinement, and pain were irrelevant to their lives was simply incomprehensible.†
p. 111.9 *

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.
For example, whenever we went to the dining car, all we could do was point to what someone else was eating or to a few incomprehensible words on the menu.†
p. 183.6

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."