Hiatus is the breaking up into two syllables of vowel combinations in
adjacent words capable of entering into synalepha. It is an extension to
the word-group of dieresis, which applies only to a single word.
Many authorities on Spanish versification recognize as hiatus various
cases which should not be so classified. In words like _yo, yerro,
hierro, huevo_, etc., the first phonetic element is in each case a
semi-vowel, and these semi-vowels have the value of consonants in the
words cited. To classify the following as examples of hiatus is to be
phonetically unsound:
Perdida tengo | yo el alma (8)
Ponzoñoso lago de punzante | hielo (12)
Me he de quejar de este | yerro (8)
Levantóse en su cóncavo | hueco (10)
Cual témpanos de | hielo endurecidos (11)
Tierno quejido que en el alma | hiere (11)
In none of these cases could there possibly be synalepha. Consequently
by definition there can be no hiatus.
Hiatus most frequently occurs to avoid the greater cacophony which would
arise from stress-shift under case 3 of synalepha: