‘恒久’ is an adjective meaning ‘long-lasting’ or ‘enduring,’ emphasizing stability and continuity over time. The first character 恒 (hénɡ) means ‘constant,’ ‘permanent,’ or ‘unwavering,’ often implying steadfastness or consistency. The second character 久 (jiǔ) means ‘long time’ or ‘for a long duration.’ Together, they form a compound that conveys deep temporal endurance—not just lengthy in duration, but also reliable and unchanging in quality. It’s commonly used to describe relationships, feelings, values, commitments, or natural phenomena that persist without fading.

This word carries a formal, literary, or poetic tone and appears frequently in written Chinese—such as essays, wedding vows, philosophical texts, or advertising slogans—but is less common in casual speech. It often modifies abstract nouns (e.g., 恒久的友谊, 恒久的爱) and rarely stands alone. Unlike simpler words like 长久 (chángjiǔ), 恒久 suggests a more profound, almost idealized permanence, sometimes with moral or emotional weight.