Synizesis is the loss of syllabicity of a vowel in hiatus.
Synizesis is the loss of syllabicity (desyllabification) of a vowel followed in hiatus, e.g. Sp. línea [ˈline̯a] ‘line’, cacao [kaˈkao̯] ‘cocoa’. Like contraction, elision and aphaeresis, it is a strategy to avoid hiatus. After synizesis, the reduced vowel often rises: Lat. habeat > It. abbia [ˈabbja] ‘may (s)he have’, Ioannes > Sp. Juan [ˈxwan] ‘John’. Synizesis can be right- or left-orientated: Lat. ego > *eo > Port. eu [eu̯], Sp. yo [ʝo] ‘I’.
The phenomenon is well atteste…