critical

noun1 of 2

being important or serious; vital; dangerous

• “It's critical to keep your mind active as you age.”Tatoeba
• “You sure guessed the critical points of that teacher's exam.”Tatoeba

Sentences from Tatoeba show real usage. A word can have several meanings, so a sentence may use another one.

adjective2 of 2

Pertaining to, or indicating, a crisis or turning point.