The spelling of the word "more prothalamic" can be explained using the International Phonetic Alphabet (IPA). The first syllable "more" is pronounced as /mɔːr/ and the second syllable "prothalamic" is pronounced as /prəʊˈθaləmɪk/. The "th" in "prothalamic" is pronounced as /θ/ which is known as the voiceless dental fricative sound. The word "prothalamic" refers to something that pertains to the early stages of a plant's development. Overall, using the IPA can help understand the pronunciation and spelling of complex words like "more prothalamic."