横綱
よこづな · yokoduna · JLPT N1 · noun
champion
🪢 横 side + 綱 rope: the top sumo rank wears a thick rope belt
Yokozuna is the highest sumo rank, and its holders wear a heavy braided rope around the waist. In the compound, tsuna becomes zuna through rendaku (sound change).
横 — wood radical 木 + 黄 (huáng, phonetic)
A semantic-phonetic compound: 木 'wood' gives the meaning (a horizontal wooden bar across a gate), while 黄 supplies the sound. It originally meant the crossbar of a gate, then extended to 'horizontal' generally. The reading hèng later developed the sense of 'unruly' or 'unexpected'.