堤防
ていぼう · teibou · JLPT N1 · noun
bank
堤 — earth radical 土 + 是 (phonetic)
A semantic-phonetic compound. The earth radical 土 signals the meaning—an embankment or dike built of earth to hold back water. The component 是 supplies the sound, historically close to the reading dī. Originally referring to riverbank levees, it now also appears in words like 堤坝 (dam).
防 — mound radical 阝(阜) + 方 fāng (phonetic)
防 is a semantic-phonetic compound. The left element 阝 (from 阜) depicts a mound or earthen embankment, suggesting barriers and defense. The right element 方 supplies the sound. Together they evoke a dike or rampart that guards against floods or attacks, hence 'to guard, prevent, defend'.