Fricatives

The fricative order comprises six elements of very diverse nature, distributed in five articulatory orders:

	Labiodental	Alveolar		Palatal	Velar	Glottal
		Dorsal	Apical
Fricatives	f	s	s̺	ʃ	x	ɦ
Spelling	f	z	s	x	j	h

Three of them are sibilant phonemes, correlates of their corresponding affricate phonemes. Therefore, the Basque language has the following sibilant subsystem:

	Alveolar		Palatal
	Dorsal	Apical
Fricatives	s	s̺	ʃ
Affricate	ts	ts̺	tʃ

As in the case of affricates, there has also been a convergence process (dephonologisation) of the alveolar series in fricatives for centuries and with the same spatial direction. In this case, the result is apical convergence.

There are voiced articulations, which vary equally in frequency and origin among dialects. In the palatal order, [ʒ] occurs in the Souletine dialect and some subdialects of the Biscay dialect resulting from the evolution of voiced approximant /ʝ̞/ in initial position, and as epenthesis in cases of hiatus. On the other hand, in the dialects of the French Basque Country, there are voice fricative sibilants in loanwords from French.

The consonant system of old Basque did not have the labiodental fricative /f/, which was gradually incorporated into various dialects over different periods of time. At present, it is not homogeneously distributed among dialects, as it does not usually appear in the eastern subdialect of Biscayan dialect, in Gipuzcoan dialect and in some subdialects of northern upper Navarrese dialect, where it is usually replaced by a voiceless bilabial plosive.

The velar fricative /x/ appeared late in the language, generally from loanwords and the evolution of the palatal approximant. It only occurs in the dialects of the Southern Basque Country, although it only has a distinctive value in Guipuzcoan dialect and in some varieties of Biscayan and northern Upper Navarrese dialects.

The glottal fricative /ɦ/, common to all dialects in ancient times, has been gradually lost over different periods of time depending on each dialect. At present, it only occurs regularly in the Souletine dialect.