Answer : the schwa
The schwa is the term given to the symbol that indicates the indeterminate vowel sound. It is also considered as the unstressed central vowel in the International Phonetic Alphabet (IPA). The schwa is also one of the most commonly misunderstood sound in the English alphabet and are known as the lazy vowels. A lot may have heard about it but only a few knows that it is the most common unaccented syllables or words in the English dialect.