Abstract noun referring to the quality of being permanent or lasting forever. Often used in formal, legal, or philosophical contexts.
This treaty guarantees the permanence of peace.
We are seeking a solution with perpetuity.
Compound of 恒久 (permanent, everlasting) and 性 (nature, quality). The exact historical derivation is uncertain, but the word follows a common pattern of forming abstract nouns from adjectives or adjectival nouns.