Definition of critical
1a : inclined to criticize severely and unfavorably His critical temperament cost him several friends.
c : exercising or involving careful judgment or judicious evaluation critical thinking a critical commentary on the mayor's proposal
d : including variant readings and scholarly emendations a critical edition
2a : of, relating to, or being a turning point or specially important juncture a critical phase : such as
(1) : relating to or being the stage of a disease at which an abrupt change for better or worse may be expected also : being or relating to an illness or condition involving danger of death critical care a patient listed in critical condition
(2) : relating to or being a state in which or a measurement or point at which some quality, property, or phenomenon suffers a definite change critical temperature
c : being in or approaching a state of crisis a critical shortage a critical situation
3a : of sufficient size to sustain a chain reaction —used of a mass of fissionable material a critical mass
b : sustaining a nuclear chain reaction The reactor went critical.
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