The spelling of the word "guster" can be explained using the International Phonetic Alphabet (IPA). The IPA transcription for "guster" is /ˈɡʌstər/. The initial "g" is pronounced with a hard "g" sound, followed by the "u" sound as in "up." The "s" sound is pronounced clearly, while the "t" is a quick and sharp sound. The final "er" sound is pronounced as one sound, with a slight emphasis on the "r." Overall, the spelling of "guster" matches its IPA transcription quite well.