CRITICAL

[adjective] - of the greatest importance to the way things might happen; dangerous or uncertainThe President's support is critical (to this project).The experiment is at a critical point/stage/juncture - we'll know the result in an hour.As long as sales remain above the critical figure of £200 000, we don't need to worry.Both drivers are critical/in a critical condition (= so badly hurt that they might die) after the 120mph crash.See also critical at critic.If a situation goes critical, it suddenly becomes extremely serious.Union leaders say that the dispute may go critical this week.Critical mass is the smallest or largest size that is necessary for something to succeed.The company has reached a critical mass and is now assured of survival.The company has reached a critical mass and must now avoid further growth.