All 4 Uses

critical
in
Educated, by Tara Westover
(Edited)

I have almost no memory of him until five years later, when I am fifteen, and he bursts into my life at a critical moment.
p. 51.7

critical = important
Later the doctors would speculate that when Dad, Luke and Benjamin had wrestled Shawn to the ground—and he'd sustained a concussion—he was already in critical condition.
p. 129.3 *

critical = serious or dangerous
I'd never heard anyone criticize my father except Shawn, and I wasn't able to respond to it.
p. 172.5 *

criticize = point to a fault in

standard suffix: The suffix "-ize" converts a word to a verb. This is the same pattern you see in words like apologize, theorize, and dramatize.
It's not a criticism.
p. 237.2

criticism = pointing to a fault

Definitions:

(1) (critical as in: a critical problem)
important, serious, or dangerous
(2) (critical as in: don't be so critical)
finding fault and telling others; or tending to have unfavorable opinions
(3) (critical as in: critical acclaim)
relating to careful analysis or thoughtful judgement of what is good and bad about something -- possibly from people whose job is to share their expert opinions in a given industry
(4) (meaning too rare to warrant focus)
See a comprehensive dictionary for more specialized senses of critical including those in mathematics and nuclear energy.