The word 小便 is formed through a direct conceptual pairing common in Chinese, where two individual characters combine to create a specific, euphemistic meaning. The first character, 小, means "small" or "minor", and the second, 便, in this context means "relief" or "convenience". Together, they form a discreet compound noun meaning "urination", literally and metaphorically "small relief", which stands in contrast to 大便 ("big relief" or defecation). This formation relies entirely on the logical, descriptive relationship between the two ideas to name a bodily function indirectly.