critical

Etymology

From Latin criticus + -al, from Ancient Greek κριτικός (kritikós, “of or for judging, able to discern”), from κρίνω (krínō, “I separate, judge”); also the root of crisis.

adj

1. Inclined to find fault or criticize.
   A good teacher is fair but critical.
2. Pertaining to, or indicating, a crisis or turning point.
   This is a critical moment.
3. Extremely important.
   It's critical that you deliver this on time.
   Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis:[…]. The evolutionary precursor of photosynthesis is still under debate, and a new study sheds light. The critical component of the photosynthetic system is the “water-oxidizing complex”, made up of manganese atoms and a calcium atom. 2013 September-October, Katie L. Burke, “In the News”, in American Scientist
   Third Pole glaciers are critical to billions of people from Vietnam to Afghanistan. File:Third Pole glaciers are critical to billions of people.ogg 2018, VOA Learning English > China's Melting Glacier Brings Visitors, Adds to Climate Concerns
4. Relating to criticism or careful analysis, such as literary or film criticism.
   The movie was a critical success, but bombed at the box-office.
   “Unless you are purchasing cereal from a health food store, many brands that are marketed as healthy are usually full of sugar and processed ingredients,” says Garcia. So when you’re choosing cereal, bread or any other whole-grain product, Garcia recommends reading labels with a critical eye. April 19, 2012, Alexandra Sifferlin, “‘Healthy’ Foods that Really Aren’t: Nutritionists Weigh In”, in Time
5. (medicine) Of a patient condition involving unstable vital signs and a prognosis that predicts the condition could worsen; or, a patient condition that requires urgent treatment in an intensive care or critical care medical facility.
   The patient's condition is critical.
6. (medicine, by extension) In such a condition.
   The patient is critical.
   Two critical after fatal Wimbledon school crash
7. Likely to go out of control if disturbed, that is, opposite of stable.
   The political situation was so critical that the government declared the state of siege.
8. (physics) Of the point (in temperature, reagent concentration etc.) where a nuclear or chemical reaction becomes self-sustaining.
   The reaction was about to become critical.
9. (physics) Of a temperature that is equal to the temperature of the critical point of a substance, i.e. the temperature above which the substance cannot be liquefied.

noun

1. A critical value, factor, etc.
   The second undamped system criticals show a greater percentage depression than the first. 1976, American Society of Mechanical Engineers, Journal of engineering for industry, volume 98, page 508
   Finally, criticals are high-risk, high-value items that give the final product a competitive advantage in the marketplace […] Criticals, in part, determine the customer's ultimate cost of using the finished product — in our example, the computer. 2008, John J. Coyle, C. John Langley, Brian Gibson, Supply Chain Management: A Logistics Perspective, page 564
2. In breakdancing, a kind of airflare move in which the dancer hops from one hand to the other.