The spelling of the word "TIGRNIST" can be explained using the International Phonetic Alphabet (IPA) transcription. The word is composed of two syllables: TIGR and NIST. The first syllable, TIGR, is pronounced /ˈtaɪɡər/, with the stressed vowel /aɪ/ and the consonants /t/, /g/, and /r/. The second syllable, NIST, is pronounced /nɪst/, with the stressed vowel /ɪ/ and the consonants /n/ and /s/. Therefore, the correct spelling of the word "TIGRNIST" reflects its pronunciation according to the IPA transcription.