How to say "perpetual" in Japanese

• 悠久ゆうきゅうCommon
  no-adjective, na-adjectiveCovers the 'eternal, everlasting' sense of perpetual: something lasting immemorially across long stretches of time. It has a lofty, literary nuance, typical of writing about history, the universe, or enduring traditions.
• 万年まんねんCommon
  noun (prefix)Matches 'perpetual' mainly in the sense of unending, year-round continuity, and appears mostly in set expressions; it is seldom the word you want for abstract or poetic senses of perpetual.

Use 悠久 for grand, poetic timelessness stretching across ages, and 万年 chiefly in fixed expressions of endless duration — each matches 'perpetual' only in its own narrow sense.

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

• 悠久ゆうきゅうeternal
• 恒久的こうきゅうてきpermanent
• 永続的えいぞくてきpermanent
• 絶え間ないたえまないincessant
• 万年まんねんperennial