異変|いへんihen[0]heiban (flat)

1. noununusual event; strange occurrence; strange phenomenon; something abnormal; change (for the worse); accident; disaster

• Synonym事変じへんWrittenA written word for a grave incident or emergency, also an undeclared armed conflict, often in historical names; 「異変」 is broader and has no war sense.
• Synonym変調へんちょうNeutralSomething being off — a change in one's condition, as in 「体の変調」 — or a musical modulation; 「異変」 is about an unusual change or event.
• Synonym変事へんじWrittenAn unexpected calamity or emergency, close in sense to 「異変」, but rare and old-fashioned in tone; in everyday speech 「異変」 is the usual choice.
• Related急変きゅうへんNeutralA sudden change — in an illness, the weather, or an attitude — or a sudden emergency. 「異変」 stresses not suddenness but that the change or event is unusual.
• Related天変地異てんぺんちいWrittenA written four-character term for major natural cataclysms such as earthquakes and floods. 「異変」 is broader, covering unusual changes in the body or society too.
• RelatedアクシデントNeutralA loanword for accidents and mishaps, often sudden trouble during a match or a trip; 「異変」 focuses on the abnormal change itself.
• Related事故じこNeutralThe everyday word for an accident, especially a traffic one. 「異変」 stresses an abnormal change and need not be an accident at all.
• RelatedもしものことCasualColloquial. The worst-case emergency, used mostly in hypotheticals like 「もしものことがあったら」; 「異変」 usually points to an abnormality that has already appeared.
• Related変災へんさいWrittenA written word for an unexpected disaster or calamity; very rare. 「異変」 does not necessarily involve damage — for everyday talk of disasters use 「災害」 or 「災難」.
• Antonym平穏へいおんNeutralCalm and untroubled, as in 「平穏な日々」; the opposite of 「異変」, which marks an abnormal turn of events.
• Antonym平常へいじょうNeutralBeing as usual, with nothing out of the ordinary, as in 「平常通り」; the opposite of 「異変」.

Use 「異変」 for an unusual change or event, as in 「体に異変を感じる」. For a sudden change say 「急変」; for an accident, 「事故」 or 「アクシデント」; when your condition is off, 「変調」. The rest are rarer or narrower: 「変事」「変災」 are written, 「天変地異」 is natural cataclysm, 「事変」 includes armed conflict, and 「もしもの事」 is the colloquial worst case.

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

1. 変かわった出来事できごと。変かわったこと。
2. 異常いじょうな変化へんかが起おこること。