瞳どう孔こうどうこうFreq.FrequencyTop 50,000Meanings1nounpupil (of the eye)anatomyAnatomical term for the opening in the center of the iris. In everyday conversation, ひとみ is more common.医い者しゃは瞳どう孔こうの大おおきさを調しらべた。The doctor checked the size of the pupil.暗くらいところでは瞳どう孔こうが開ひらく。In the dark, the pupil dilates.