A voiceless postalveolar fricative is a type of consonantal sound used in some spoken languages.

It also features in the orthographies of many Baltic, Finno-Samic, North American and African languages.

Features of the voiceless palato-alveolar fricative: In various languages, including English and French, it may have simultaneous labialization, i.e. [ʃʷ], although this is usually not transcribed.

For instance, Proto-Germanic *skipą ("hollow object, water-borne vessel larger than a boat") was pronounced /ˈski.pɑ̃/.

This change took longer to catch on in West Germanic languages other than Old English, though it eventually did.

Then, most likely through influence from German and Low Saxon, North Frisian experienced the shift.

Then, Swedish quite swiftly underwent the shift, which resulted in the very uncommon [ɧ] phoneme, which, aside from Swedish, is only used in Colognian, a variety of High German, though not as a replacement for the standard High German /ʃ/ but a coronalized /ç/.