Definition: an outer room that is connect to an inner room, often used for waiting.
Example: She sat in the poorly decorated anteroom, awaiting her appointment.
Rarity: bottom 40% of words in common usage (Merriam-Webster).
Etymology: 1762, ante (Latin: before) + room
Word in Use: “Despite the ruling, party investigators went into a detailed hypothesis as to what took place in the anteroom between Hookem and Woolfe.”(https://www.rt.com/uk/364172-woolfe-hookem-ukip-fight/)
Across languages: Spanish: antesala; in use: “Pizzi ratifica a Sánchez, Vidal y Bravo en la antesala del partido ante Uruguay” (http://www.elmostrador.cl/noticias/pais/2016/11/14/pizzi-ratifica-a-sanchez-vidal-y-bravo-en-la-antesala-del-partido-ante-uruguay/)
German: Vorzimmer; in use: “in eine Kommodenlade im Vorzimmer und wartete ab.” (http://www.kleinezeitung.at/oesterreich/5118569/Wien_Putzfrau-soll-Pensionistin-mehr-als-100000-Euro-gestohlen-haben)
Why I like this word: I think it is a relatively useful and interesting word, the alternative “antechamber” is used slightly more often. I think both words should be used a bit more to befit their rather considerable utility, for example instead of calling it a waiting room why not be more lexically economical and call it the anteroom?