The vowel sounds are: ra and lam

The answer is: Correct, it is six letters (yaa - ra - meem - lam - waw - noun).

The definition of diphtheria linguistically is: (inserting something into something), and its definition idiomatically is: (the meeting of a consonant letter with a vowel letter so that they become like one stressed letter). (yaa - ra - meem - lam - waw - noon) were collected together in the word (ramlon).