The spelling of the word "mattest" is quite easy to understand if you know the phonetic transcription of the word. "Mattest" is pronounced as "mat-ist" in IPA, where the stress is on the first syllable, and the final "t" is silent. The suffix "-est" is added to the adjective "mat" to create the superlative form, which means the most matte. This word is commonly used to describe the texture or finish of various materials, such as makeup, paint, or surfaces.