The spelling of the word "Cerchnus" can be explained using the International Phonetic Alphabet (IPA). The first syllable of the word is pronounced as /ˈsɛrk/, where the "c" is pronounced as an "s" and the "h" is silent. The second syllable is pronounced as /nəs/, where the "ch" is pronounced as a "k". So, the correct spelling of this word would be "Cercnus" instead of "Cerchnus", since the "h" is not actually pronounced in the word.