ob·stru·ent 
(ŏbstr-ənt)
(ŏbstr-ənt)adj.
Obstructing or closing natural openings or passages of the body.
n.
1. An obstruent medicine or agent.
2. Linguistics A sound, such as a stop, fricative, or affricate, that is produced with complete blockage or at least partial constriction of the airflow through the nose or mouth.
[Latin obstruēns, obstruent-, present participle of obstruere, to obstruct; see OBSTRUCT.]