九

九 is a pictographic/indicative character. It is thought to depict a bent arm or hook-like shape, representing the concept of reaching a limit or end. Over time, it came to represent the number nine, the largest single-digit number. In oracle bone script and bronze inscriptions, the character 九 resembled the shape of an elbow. Today, the character specifically meaning "elbow" is 肘.
Related characters: - end or extreme point; - number nine; - symbol of completeness or abundance.

구월 (九月) — September

구십 (九十) — ninety

구층 (九層) — nine floors

Because 9 is the largest single-digit number, it can also carry the meaning of many or abundant. Additionally, due to its similar pronunciation to 久 ("long-lasting" or "enduring"), it can also imply longevity or something old.

A variant or associated character is 玖, which originally means "jade stone" but shares the same pronunciation and is thus used as a homophone.

In many East Asian traditions, nine symbolizes longevity and completeness.

It often appears in historical, cultural, and symbolic contexts (e.g., imperial symbolism in China).

In China, 九 is also used as slang for alcohol (酒, jiǔ), simply because they sound the same.