The word "rummier" is spelled with a double "m" to indicate the "m" sound is pronounced twice in rapid succession. This is known as a geminate consonant, which is indicated in IPA phonetic transcription by placing a double consonant symbol between two identical consonant sounds. In the case of "rummier," the IPA symbol for the geminate consonant is /mː/, which represents the prolonged pronunciation of the "m" sound. It is important to use correct spelling and phonetic transcription to accurately convey the intended pronunciation of words.