A fricative is a consonant produced by forcing air through a narrow channel made by placing two articulators close together.
Fricatives usually develop from plosives under the following conditions:
- / #_C in Avestan
- / _# in Gothic
- / V_V in Irish
When a language distinguishes aspirated and unaspirated plosives, either series might become a fricative (the former occured in Greek, the later in Germanic).