The word "checkiest" is spelled with the letter "ch" followed by the letters "eck" and the suffix "-iest". The phonetic transcription of "checkiest" is /ˈtʃɛkiɪst/. The "ch" sound is pronounced as the sound in the word "chat". The "eck" sound is pronounced as the sound in the word "check". The suffix "-iest" indicates the superlative form of an adjective, which means "most check-like". While this word may not be commonly used, it is a valid word in the English language.