"Bittiest" is spelled with two "t"s and two "i"s. In IPA phonetic transcription, it would be written as /ˈbɪtiɪst/. The double "t" represents the doubled consonant sound in the middle of the word, while the double "i" represents the vowel sound being held slightly longer than a single vowel sound. This word is a superlative form of "bitty," meaning very small or tiny. "Bittiest" is used to describe the smallest of the small, the tiniest of all.