The word 合约 is formed by combining two characters, each contributing a core idea to create a unified concept. The first character, 合 (hé), fundamentally means to join, combine, or bring together. The second, 约 (yuē), carries the essential meaning of a promise, agreement, or mutual pledge. Their union in 合约 conceptually represents the coming together of promises or terms into a single, binding joint agreement, a contract. The formation is not merely additive; it reflects a traditional conceptual model where an agreement is seen as a harmonious fusion of mutual commitments.