昨天
zuó tiān · HSK 1
yesterday
📅 昨天 = 昨 (previous) + 天 (day) — literally 'previous day'
昨 means the day just past; 天 means day or sky. Together they form the standard word for yesterday. Compare 今天 (today) and 明天 (tomorrow), which share the same 天 suffix.
天 — 一 (one/sky) above 大 (big person)
Originally a pictograph of a person (大) with an emphasized head, representing what is above — the sky or heavens. The top stroke evolved into 一, symbolizing the vast expanse overhead. From 'sky' it extended to mean 'day,' 'heaven,' and 'nature.'