裏切る
うらぎる · uragiru · JLPT N3 · verb-godan
to betray
🗡️ 裏切る = back side (裏, ura) + cut (切る, kiru): to cut someone from behind
裏 means the back or hidden side of something, and 切る means to cut. Betrayal is cutting someone from the side they cannot see, like the English phrase to stab someone in the back. The sounds blend: ura + kiru becomes uragiru.
切 — 七 (phonetic) + 刀 (knife radical)
切 is a semantic-phonetic compound: 刀 'knife' gives the meaning of cutting, while 七 supplies the sound. The original sense was to slice or cut with a blade. From there it extended figuratively to 'close to' (as in pressed against) and 'urgent/earnest', as in 切实.