有事|ゆうじyuuji[1]atamadaka (head-high)

1. nounemergency

• SynonymエマージェンシーNeutralLoanword for emergencies, common with equipment and in medical settings; 「有事」 is reserved for major upheavals like war or unrest.
• Synonym危機ききNeutralA crisis that threatens survival, with a broad range of uses; 「有事」 focuses specifically on the outbreak of war or unrest.
• Synonym非常ひじょうNeutralCovers emergencies and unusual situations, as in 「非常口」; to express degree, use the adverb 「非常に」.
• Synonym非常時ひじょうじNeutralA critical period of war, disaster or the like; close to 「有事」, which is the usual term in security and defense contexts.
• Synonym急場きゅうばNeutralAn urgent moment demanding immediate action, as in 「急場をしのぐ」; mostly used at the personal level.
• Synonym危急ききゅうWrittenWritten/formal prose with a heavy tone, for danger closing in, as in 「危急存亡」.
• SynonymピンチNeutralLoanword for a tight spot or predicament, mostly about individuals or matches, though a country can be in one too; it cannot simply replace 「有事」.
• Synonym不虞ふぐWrittenWritten/formal prose and rare, for the unexpected or unforeseen, usually as 「不虞の事態」.
• Synonym変事へんじWrittenWritten/formal prose for abnormal events or calamities, often seen in historical narrative.
• Synonym緊急事態きんきゅうじたいNeutralA state of affairs needing urgent response, such as a government-declared state of emergency; broader in scope than 「有事」.
• Synonymまさかの時まさかのときNeutralColloquial, for when something goes wrong out of the blue, as in 「まさかの時に備える」.
• Synonym緊急時きんきゅうじNeutralThe point in time when an emergency strikes, as in 「緊急時の連絡先」; the focus is on the timing.
• Related急変きゅうへんNeutralA sudden change in illness, weather, attitudes or the situation, not necessarily for the worse; also a sudden accident. The stress is on abruptness.
• Related焦眉しょうびWrittenWritten/formal prose. Usually in the set phrase 「焦眉の急」, for an urgent matter that brooks no delay.
• Related火急かきゅうWrittenWritten/formal prose, for matters of the utmost urgency, as in 「緊急火急」.
• Antonym平時へいじNeutralPeacetime or ordinary times, the standing opposite of 「有事」, as in the pairing 「平時と有事」.
• Antonym平穏へいおんNeutralCalm and uneventful, the opposite of the turbulence implied by 「有事」.

Use 「有事」 for major upheavals like war or unrest; it pairs with 「平時」. For ordinary emergencies say 「緊急時」 or 「非常時」; 「緊急事態」 is broader still, and 「非常」 turns up in compounds like 「非常口」. 「危機」 is a wide-ranging crisis, 「ピンチ」 a personal or competitive tight spot, 「エマージェンシー」 a loanword for equipment and medical settings. 「急変」 is a sudden change, 「急場」 a moment demanding quick action, 「まさかの時」 a colloquial just-in-case. Written/formal: 「焦眉」, 「危急」, 「火急」, 「不虞」, 「変事」. Opposites: 「平時」, 「平穏」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 戦争せんそうや騒乱そうらんなどの事変じへんがあること。