乳突 rǔtū mastoid process Origin Definitions Defs Strokes Stroke Words Sentences Sents 乳突窦 rǔtūdòu mastoid antrum mastoid antrum; the air space in the mastoid bone behind the middle ear人类乳突病毒 rénlèirǔtūbìngdú HPV human papillomavirus; the virus responsible for a common sexually transmitted infection