Anterior

Anterior is a feature which characterizes phonemes that are produced with an obstruction located in the front of the palato-alveolar region of the mouth. The palato-alveolar region is where the ordinary /'cup'-s/ is produced.

Example
Anterior sounds in English are /p/, /b/, /m/, /t/, /d/, /n/, /f/, and /v/.

Link
Utrecht Lexicon of Linguistics