TSUMUGU · TOCFL 1 · 字
昨
昨 ＝ 日 ＋ 乍
ㄗㄨㄛˊ · zuó
noun — yesterday
字源 FORM — what the parts do
乍聲gives the sound
IFTzhà → zuó — 乍's family runs wide: 作、昨、炸、詐
Days (日) already gone — 說文 glosses 昨 as 累日, days piled up behind. 乍 gives the sound, zhà worn to zuó. The pile narrowed to the day just past: 昨天、昨晚.
故事 STORY — a scene to remember it by
太陽（日）落了又升，中間那一天，再也走不回去。
The sun (日) sets and rises again; the day between is out of reach.
字源記憶法
意 · Meanings
(本義)累日— days piled behind
→昨天、昨日— yesterday常用
→昨晚— last night
(本義) original meaning · → ⇒ each arrow = one more step of extension