長期|ちょうきchouki[1]atamadaka (head-high)

1. no-adjectivelong-term
   長期ちょうきにわたる病気びょうきのあとでジェーンはカウチ・ポテトになった。↗

   After being ill for a long time, Jane turned into a couch potato.

• Synonym長年ながねんNeutralOften adverbial: 「長年の夢」「長年勤める」. Points to the many years already lived through.
• Synonym多年たねんWrittenWritten/formal prose for many years, as in 「多年にわたる研究」; more formal than 「長年」.
• Synonym積年せきねんWrittenWritten/formal prose for years of accumulation, mostly modifying grudges and entrenched problems: 「積年の恨み」.
• Synonym長い間ながいあいだNeutralThe everyday way to say a long time: 「長い間お世話になりました」.
• Synonym長期間ちょうきかんNeutralA very long period of time, stressing the length itself; compounds like 「長期計画」 normally take 「長期」.
• Synonym永年えいねんWrittenWritten/formal prose; the same word as the first entry, read 「ながねん」 and also written 「永年」. Stresses years already lived through; 「長期」 is said of plans and contracts.
• Related年月としつきNeutralThe passing years and months, stressing the flow of time: 「長い年月が経つ」.
• Related千秋せんしゅうWrittenWritten/formal prose for a thousand years; seen in 「一日千秋」, which describes anxious waiting.
• Related百年ひゃくねんNeutralLiterally a hundred years, but also a metaphor for an extremely long time, as in 「百年の恋も冷める」.
• Related千載せんざいWrittenWritten/formal prose for a thousand years; seen in 「千載一遇」, meaning an extremely rare chance.
• Related百世ひゃくせいWrittenWritten/formal prose for a hundred generations, countless ages; mostly in phrases about passing things down to posterity, rare in everyday use.
• Related長日月ちょうじつげつWrittenWritten/formal prose but rarely used; refers to long years and months. Normally say 「長い年月」 instead.
• Related千歳ちとせWrittenWritten/formal prose; same word as the 「千載」 entry above, also written 「千歳」. Means eternity, close to 「長期」 only in the sense of vast time; mostly in fixed expressions.
• Antonym短期たんきNeutralThe direct opposite of 「長期」: short-term, as in 「短期留学」.
• Antonym短期間たんきかんNeutralA short stretch of time, the opposite of 「長期間」: 「短期間で上達する」.

Use 「長期」 for long-term plans, contracts and the like. To look back on the years already spent, say 「長年」; in everyday speech, a long time is 「長い間」; in written prose, many years is 「多年」.

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

1. 長ながい期間きかん。