critical
adj.adj. very important or necessary for something to succeed. It can also describe someone who finds faults or a situation that is dangerous.
adj. expressing adverse or disapproving comments or judgements; alternatively, describing a point of crucial importance or a state of crisis.
The first few minutes of the meeting are critical.
The patient remains in critical condition, but doctors are hopeful that the new treatment will stabilize her by morning.
While the director welcomed honest feedback, she found the lead critic's review to be unnecessarily critical of the production's minor technical flaws rather than its artistic merits.
From Latin criticus + -al, from Ancient Greek κριτικός (kritikós, “of or for judging, able to discern”), from κρίνω (krínō, “to separate, judge”); also the root of crisis.
When meaning 'crucial', it often takes the preposition 'to' or 'for'. When meaning 'disapproving', it typically takes 'of'.
He was critical about my work.He was critical of my work.When expressing disapproval, the adjective 'critical' is conventionally followed by the preposition 'of'.