A Chabadnitze (Yiddish: חב"דניצע, also known as a חדר שני (Cheder sheini) "second room" in Hebrew) is a small side room required for a Chabad synagogue. It is designated specifically for those who wish to pray at length, in the Chabad tradition of meditation, in a quiet setting. Accordingly, the sixth Lubavitcher Rebbe, Rabbi Yosef Yitzchok Schneersohn related:
References
Chabadnitze Wikipedia(Text) CC BY-SA