What is the Meaning & Definition of diphthong

It is diphthong in Phonetics when we find ourselves in the presence of two vowels together in the same syllable. For a diphthong is really such, the combination of vowels (such as ae, ai, oa, io, ou, ei, ia, ua and many others) must be composed of a weak vowel and a strong vocal, difference that is marked in the pronunciation of the word. However, there are also homogeneous diphthongs which are a combination of two weak vowels put together (the presence of two strong vowels is not known as a diphthong homogeneous if not that the syllable is separated in this case). The word diphthong comes from Greek - dipthongos - word that means 'two sounds' or 'two tones'. Diphthongs may be formed by different types of vowels and can then receive different names. The three types of best-known diphthongs are falling diphthongs (those which start with a strong vocal and end up decreasing towards a weak vowel), diphthongs open and closed (which vary in how the sound is produced ultimately, open or closed mode if) and, finally, the Central diphthongs (those in which the diphthong closes with a sound more central than at the beginning).
Diphthongs differ from the monotonous vowel sounds since these vowels are enclosed by consonants, as in the case of 'theft' or 'mouth'. It is important to also point out that the presence of the consonant H, in the Spanish language, not prevents the formation of diphthongs since it is silent and in Phonics does not represent any sound. At the same time, the and (Greek) can be used as a vowel exceptional if it falls at the end of the word (as in 'hay') and therefore form a diphthong. Not so if it appears at the beginning, where their sound is altered and acts as a consonant (for example, in the case of 'grass').