短信
duǎn xìn · HSK 2
text message
📱💬 短 (short) + 信 (letter/message) = short letter = SMS
短 means short or brief; 信 means letter or message. Together they literally spell out short letter, which is exactly what a text message is. The xìn in 信 also shows up in 信件 (mail) and 微信 (WeChat).
短 — arrow 矢 + bean/vessel 豆
Originally a phono-semantic compound: 矢 (arrow) gives the meaning, since arrows were used as a short measuring stick, while 豆 (an ancient stemmed vessel) supplied the sound. From 'short in length' the meaning broadened to 'short' in time, stature, or quality.
信 — person 亻 + speech 言
信 combines 亻(person) with 言(speech), depicting a person standing by their words. The original sense is 'truthfulness' or 'sincerity'—what a person says can be trusted. From this it extended to 'believe,' 'trust,' and later 'message' or 'letter,' since a letter carries one's word.