Chinese character 忐

It points to unease, usually as part of 忐忑. In Chinese, 忐 is chiefly used as the first character in 忐忑, meaning uneasy or apprehensive, and in phrases such as 忐忑不安. Alone, it reads like a clipped pointer to the same unsettled feeling.

An early written form of the compound is 憳忒, recorded in 集韻, a Song-era Chinese dictionary, with the sense “the heart is not at peace.”

Both characters place 心 (“heart”) below a different top part: 忐 has 上 (“up”), and 忑 has 下 (“down”), giving the compound an up-and-down image of unease. A separate character written 忑 appears in bronze inscriptions (writing cast or carved on objects) from China's Warring States period, including as a personal name. That distinct character does not establish the origin of 忐忑.

Someone sent me just 忐—what does it mean?

Treat it as a clipped reference to unease. Since 忐 usually appears as the first half of 忐忑, a lone 忐 may be playful shorthand or an unfinished thought. If the context is unclear, ask whether they meant 忐忑 or 忐忑不安.

Use 忐忑 for the complete expression. A lone 忐 assumes the reader will supply its partner, so it works best when you both know the wordplay.