The spelling of the word "thurner" can be explained using the International Phonetic Alphabet (IPA). According to IPA, "thurner" is spelled as /ˈθʊrnər/. This means that the first syllable of the word is pronounced with a voiceless dental fricative, represented as "th" in English. The second syllable is pronounced with a short u sound followed by an r sound, represented as /ʊr/. The final syllable is pronounced with a schwa sound, represented as /ə/. Overall, the pronunciation of "thurner" is /θʊr-nər/.