There is no H in the Greek alphabet. However, the H sound did exist. An H sound sometimes existed at the beginning of a Greek word that contained a vowel as the first letter in the word. In order to represent the H sound, Greek uses an accent mark that looks like an apostrophe. The Greek letter H is named eta.

h in British English 1. the eighth letter and sixth consonant of the modern English alphabet. 2. a speech sound represented by this letter, in English usually a voiceless glottal fricative, as in hat.