Zen-dō (禅堂?) (Chinese: Chántáng) or senbutsu-jō (選仏場?) is a Japanese term translating roughly as "meditation hall". In Zen Buddhism, the zen-dō is a spiritual dōjō where zazen (sitting meditation) is practiced. A full-sized Zen Buddhist temple will typically have at least one zen-dō as well as a hon-dō ("main hall", but sometimes translated as "Buddha hall"), which is used for ceremonial purposes, plus a variety of other buildings with different functions. However, any place where people go to practice Zen can be referred to as a zen-dō.
Read more about Zendo: Zen-dō Mealtimes