Synalepha
A synalepha or synaloepha is the merging of two syllables into one, especially when it causes two words to be pronounced as one.
The original meaning in Ancient Greek is more general than modern usage and includes coalescence of vowels within a word. Similarly, synalepha most often refers to elision, but it can also refer to coalescence by other metaplasms: synizesis, synaeresis or crasis.Examples
Spanish, Portuguese and Italian use synalepha; this is important when counting syllables in poetry. For instance in this hendecasyllable by Garcilaso de la Vega:
The words que and al form one syllable when counting them because of the synalepha. The same thing happens with -ro and os-, so that the line has eleven syllables :
