Meaning:

exchange; convert; add (water, etc.)

Origin:

“兑”是“悦”的本字，字形的下半是一个人，上半突出了他的嘴和嘴角的笑纹。现在另有“悦”字表示喜悦，“兑”的意思为换取。

“兑” is the original version of the character “悦.” The lower part is a person and the upper part is an exaggeration of a laughing mouth. Today, the character “悦” expresses joyfulness, while the meaning of “兑” is “to exchange.”

Words:

   兑水  (duì shuǐ) : to water down

   兑现  (duìxiàn)  : cash

   兑换 (duìhuàn): to exchange

Examples:

1. 这杯酒是不是兑水了？一点儿味道都没有。

    Zhè bēi jiǔ shìbúshì duìshuǐ le ？Yīdiǎnr wèidào dōu méiyǒu

    Has this glass of wine been watered down? It has no taste whatsoever.

2. 我做出的承诺一定会兑现的。

    Wǒ zuòchū de chéngnuò yīdìng huì duìxiàn de

    I will honor my commitment.