hiatus
/haɪˈeɪtəs/
A gap in a series, making it incomplete.
An interruption, break or pause.
An unexpected break from work.
A gap in geological strata.
An opening in an organ.
Hiatus aorticus is an opening in the diaphragm through which aorta and thoracic duct pass.
A syllable break between two vowels, without an intervening consonant. (Compare diphthong.)
Words like reality and naïve contain vowels in hiatus.