critical

forming or having the nature of a turning point or crisis

“a critical point in the campaign”

urgently needed; absolutely necessary

“a critical element of the plan”

at or of a point at which a property or phenomenon suffers an abrupt change especially having enough mass to sustain a chain reaction

“a critical temperature of water is 100 degrees C--its boiling point at standard atmospheric pressure”

being in or verging on a state of crisis or emergency

“a critical shortage of food”

characterized by careful evaluation and judgment

“a critical reading”

marked by a tendency to find and call attention to errors and flaws

“a critical attitude”

of or involving or characteristic of critics or criticism

“critical acclaim”