entries → 哦
TSUMUGU · TOCFL 1 (est.) · 字
哦 character · TOCFL 1 (est.)
哦 ＝ 口 ＋ 我
ㄛˊ · ó
interjection — oh (understanding); oh? (mild doubt)

字源 FORM — what the parts do

口義a mouth, the sound it makes
我聲wǒ — gives the sound
IFTwǒ → ó — the mouth-sound bent the whole reading
A sound out of the mouth (口) — the "oh" of catching on, or of half-doubt. 我 wǒ supplies the frame, the same donor under 峨 and 鵝, bent into a bare vowel here.

故事 STORY — a scene to remember it by

聽懂了，嘴（口）順口應一聲：「哦——」
It clicks; the mouth (口) lets out an easy "oh."
字源記憶法
意 · Meanings
(假借)哦，原來如此— oh — now I get it常用
(假借)哦？真的嗎— oh? — mild doubt常用
(本義) original meaning · → ⇒ each arrow = one more step of extension
關 · Related
喔＝ 口 ＋ 屋ōthe sister exclamation — 喔 holds 屋, 哦 holds 我峨éshares the 我 donor — a high peak, not a sound