填补
tián bǔ · HSK 7
to fill a gap
🕳️🩹 填 fill + 补 patch/mend = fill a gap, patch a hole or deficiency
填 (tián) means to fill or stuff; 补 (bǔ) means to mend, patch, or supplement (as in 补充). Together they cover both filling a blank on a form and making up for a shortfall.
填 — earth 土 + 真 (zhēn, phonetic)
填 is a semantic-phonetic compound. The 土 (earth) radical signals the meaning—filling in with soil—while 真 supplies the sound (originally close to 'tian'). The original sense was to stuff or pack a hole with earth, later broadened to filling in any gap, form, or blank.
补 — clothes radical 衤 + 甫 (phonetic)
补 is a phono-semantic compound. The left side 衤 (clothes radical) gives the meaning, originally referring to patching or mending clothes. The right side 甫 supplies the sound. From 'mend a garment' the meaning broadened to 'repair, supplement, make up for'.