鈍感
どんかん · donkan · JLPT N1 · na-adj
thickheadedness
感 — heart 心 + 咸 (xián, phonetic)
A semantic-phonetic compound. The heart radical 心 at the bottom carries the meaning of feeling or emotion, while 咸 supplies the sound. Together 感 conveys being moved in the heart, hence 'to feel,' 'sense,' or 'be affected by' something.