An obstruent (/ˈɒbstruənt/ OB-stroo-ənt) is a speech sound such as [k], [d͡ʒ], or [f] that is formed by obstructing airflow. Obstruents contrast with sonorants, which have no such obstruction and so resonate. All obstruents are consonants, but sonorants include vowels as well as consonants.

Obstruents are subdivided into:

Obstruents are often prototypically voiceless, but voiced obstruents are common. This contrasts with sonorants, which are prototypically voiced and only rarely phonemically voiceless.