It is a separation, a hollow, a void, but it has very specific uses in Spanish. Colloquially "to have a hiatus" is "to have a lapse, to go blank for a moment". For anatomy it is a cleft, such as in the mouth or vulva. In language and its metric is the separation of vowels joined by a diphthong into different syllables. It is commonly used in poetry to lengthen a verse and is marked with a tilde on a weak vowel. The name is of Latin origin for hiatus, us ("interruption, cut"), which comes from hio, as, are ("to cleave, open, crack").