exchange

兌 is formed from 兄 (elder brother) with two additional strokes. 兄 depicts a person standing and speaking, while the two strokes represent dimples or a smile, making 兌 a pictograph of a person speaking with a smile. Originally, 兌 carried the meaning of joy or happiness, but this sense was later taken over by the character 悅 (pleasure). Nowadays, 兌 specifically refers to exchange; when exchanging items with another to obtain what one desires, a pleasant and amiable demeanor is naturally required.