Sentence:  The <WSD>Vestibule</WSD> (vestibulum nasi). — The paired <WSD>vestibule</WSD> may be considered an antechamber to the nasal fossa. 
Meaning of the word marked with <WSD> tags:  (body cavity) Any of a number of body cavities, serving as or resembling an entrance to another bodily space. (from the 18th c.)