Yeísmo

[2] Similar mergers exist in other languages, such as French, Italian, Hungarian, Catalan, Basque, Portuguese or Galician, with different social considerations.

[6] In most of Argentina and Uruguay, the merged sound is pronounced as a voiced postalveolar fricative [ʒ];[7] this is referred to as zheísmo.

The [ʒ] sound itself may have originated in Argentina and Uruguay as an influence from the local Amerindian languages on the colonial Spanish spoken by the area's inhabitants of that time; the pronunciation then persisted after the mass immigration of post-colonial Italians, Germans, Spaniards and more into the region, which effectively transformed the region's demographics and affected various aspects of the Spanish language there, including (most noticeably) intonation.

Prior to this post-colonial mass immigration wave, like most other South American countries, the populations of Argentina and Uruguay were similarly composed of a mestizo majority (those of mixed Spaniard and Amerindian ancestry); in Buenos Aires, the [ʒ] sound has recently been devoiced to [ʃ] (sheísmo) among younger speakers.

Comparatively, within the Ecuadorian Sierra region (spanning from the Imbabura to the Chimborazo Provinces, where the pronunciation of /ʎ/ as [ʒ] survives among the majority population of colonial-descended mestizos), the sibilant has not merged, as in Argentina and Uruguay; a distinction is also maintained, but with ⟨ll⟩ representing [ʒ], rather than the original Spanish [ʎ] sound, and ⟨y⟩ representing [ʝ].

This three-way distinction is still present in the Quechua of more southerly regions, such as the Azuay province, which uses the graphemes , , and to distinguish between these phonemes.

[13] By 1989, several traditionally non-yeísta areas, such as Bogotá and much of Spain and the Canaries, had begun rapidly adopting yeísmo, in the span of little more than a single generation.

[13] In Spain, most of the northern half of the country and several areas in the south, particularly in rural Huelva, Seville, Cádiz, and part of the Canaries used to retain the distinction, but yeísmo has spread throughout the country, and the distinction is now lost in most of Spain, particularly outside areas in linguistic contact with Catalan and Basque.

In monolingual, urban northern Spain, a distinction between /ʝ/ and /ʎ/ only exists among the oldest age groups in the upper classes.