The Chinese word **兑换 (duìhuàn)**, meaning "to exchange" or "to convert" (often used for currency), is a **compound word formed by combining two synonymous characters to reinforce a specific meaning**. The first character, **兑 (duì)**, originally depicted a person speaking joyfully (引申义 yǐnshēnyì, extended meaning) and carries the core idea of "exchange" or "convert." The second character, **换 (huàn)**, means "to swap," "to trade," or "to change." When paired, they create a **parallel or coordinative compound (并列结构 bìngliè jiégòu)** where each character contributes a similar semantic notion, together precisely denoting the action of exchanging one item for another, especially of equivalent value, resulting in a term more specific and nuanced than either character alone.