The spelling of the word "ISTIC" can be explained through its phonetic transcription in IPA. The first sound is "ɪ" which sounds like the "i" in "bit". The next sound is "s" which sounds like the "s" in "sun". The third sound is "t" which sounds like the "t" in "tea". The fourth sound is "ɪ" which, as previously mentioned, sounds like the "i" in "bit". And the final sound is "k" which sounds like the "k" in "kite". Together, these sounds create the spelling of the word "ISTIC".