entries → 欸
TSUMUGU · C1 (est.) · 字
欸 character · C1 (est.)
欸 ＝ 欠 ＋ 矣
ㄟˋ · èi
interjection — hey; (also) a sigh

字源 FORM — what the parts do

欠義a person with mouth open — a breath, a call
矣聲yǐ — gives the soundthe classical end-particle
IFyǐ → èi — the reading shifted off the donor
A mouth thrown open (欠) for the breath pushed out — first a scolding-cry, then a sigh, and now the call thrown across a room: 欸，你來。矣 yǐ carries the sound, shifted to èi.

故事 STORY — a scene to remember it by

隔著屋子，嘴一張（欠）喊一聲——欸！
Across the room, the mouth opens (欠) for a single call — hey!
字源記憶法
意 · Meanings
(本義)欸嘆— a sigh, a lament
→欸（招呼）— hey — a call, an answering cry常用
(本義) original meaning · → ⇒ each arrow = one more step of extension
關 · Related
唉＝ 口 ＋ 矣āithe lookalike — 唉 takes a mouth (口); 欸 takes the breath-figure (欠)矣yǐthe sound donor, bare — the classical end-particle