KanjiJLPT N1
Hamper

disturb, prevent, hamper, obstruct

Mnemonic

A woman stands in the doorway wielding a giant compass like a barricade, determined to hamper anyone from getting through. She swings the compass side to side, blocking every attempt to pass. The woman hampers all progress with ruthless precision.
Additional thoughts
Picture the woman physically using an oversized compass as a swinging barrier in a narrow doorway. The compass needle arm sweeps back and forth—no one can slip past. Woman + compass = obstruction.
Quick recall
A woman swings a compass across the doorway to hamper all who try to pass.

Details

The keyword for 妨 is hamper. This kanji conveys the idea of obstructing, hindering, or getting in the way of something. It refers to any action or force that impedes progress, interferes with plans, or prevents something from proceeding smoothly. The sense is one of creating an obstacle or disturbance that makes it difficult for someone to accomplish what they intend.
On'yomi
ぼう
Kun'yomi
さまた.げる