幻を追う[maboroshiwoou] to pursue an illusion
幻影[genei] phantom
幻覚[genkaku] hallucination
幻覚剤[genkakuzai] hallucinogen
幻姿[genshi] apparition

幻視[genshi] visual hallucination
幻想[gensou] illusions
幻想劇[gensougeki] non-realistic drama
幻像[genzou] phantom

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