The spelling of the word "c w" is unique as it is a Welsh word that uses two letters not commonly used in English. In IPA phonetic transcription, "c w" is represented as [kuː]. The "c" is pronounced with a hard "k" sound, while the "w" is pronounced similarly to the English "oo" sound. This word is commonly used in Welsh to refer to a dog's bark. It is important to note that the spelling of Welsh words can be tricky for English speakers due to its distinct phonetic system.