KanjiJLPT N1
Intimidate

menacing, dignity, majesty, threaten

Mnemonic

Open your mouth wide and scream until your face turns red — no, even redder than red, a blazing double-crimson fury. That savage roar from your mouth, glowing red upon red, is enough to intimidate anyone into trembling silence.
Additional thoughts
Picture a face with mouth gaping, flushed red twice over — layered crimson rage. Two reds stacked beside a mouth perfectly mirrors the kanji structure: 口 + 赤赤.
Quick recall
A gaping mouth flushes red upon red to intimidate all into silence.

Details

The keyword for 嚇 is intimidate. This kanji conveys the idea of threatening, frightening, or menacing someone into submission through displays of power or aggression. It carries a sense of coercion, where fear is deliberately instilled to influence another person's behavior. The character suggests a forceful, overbearing approach meant to overwhelm and cow others into compliance.
On'yomi
かく
Kun'yomi
おど.す