The word "gassinesses" describes the quality or state of being excessively gaseous. Its spelling can be confusing due to the repetition of the letters "s" and "e." The first syllable is pronounced with a soft "g" followed by the short "a" sound, represented by the IPA symbol /æ/. The double "s" is pronounced as a hissing sound, /s/, and the final syllable rhymes with "dresses," with the long "e" sound represented by /iː/. So, the IPA transcription of "gassinesses" is /ˈɡæsɪnɪsɪz/.