胸腔[kyoukou] thorax
口腔外科[koukuugeka] dental surgery
耳腔[jikou] inside the ear
体腔[taikou] body cavity
体腔壁[taikouheki] body wall

内腔[naikou] lumen (anatomical)
口腔[koukou] the oral cavity
鼻腔[bikou] the nasal cavity
腹腔[fukkou] abdominal cavity
口腔癌[koukougan] oral cancer

偏芯[henshin] eccentricity (in mechanics, electronics, etc.)
燈芯[toushin] (lamp) wick
帯芯[obishin] thick obi sash
摘芯[tekishin] thinning (buds and branches)
芯地[shinji] padding

替え芯[kaeshin] spare lead
鉛筆の芯[enpitsunoshin] lead of a pencil
硬の芯[kounoshin] hard pencil lead
林檎の芯[ringonoshin] core of an apple