The spelling of the word "TISISI" can be explained using IPA phonetic transcription. The first letter "T" represents the voiceless alveolar stop consonant /t/. The following letters "IS" indicate the pronunciation of the sound /ɪz/, which is a voiced alveolar fricative followed by a vowel. The final letter "I" represents the short vowel sound /ɪ/ again. Therefore, the word "TISISI" can be pronounced as /tɪzɪsi/.