The word 永恒 (yǒnghéng) is formed by combining two independent characters, each contributing a core aspect of the concept. The first character, 永, carries the inherent meaning of "perpetual" or "long-lasting", evoking a sense of unending duration. The second character, 恒, adds the dimension of "constant", "unchanging", or "persistent", emphasizing steadfastness and stability. Their union is not merely additive but synergistic, fusing the idea of endless time with the quality of immutable constancy to create the single, profound concept of "eternity" or "perpetuity".