The word "yessest" is an old English conjugation of the verb "to be". It is no longer in use today, but its spelling can be explained through IPA phonetic transcription as /ˈjɛs ɪst/. The first syllable "yes" is pronounced with an open "e" sound as in "yet", and the second syllable "sest" is pronounced with a short "i" sound as in "sit", followed by a soft "s" sound. Despite its archaic nature, "yessest" demonstrates the evolution of the English language and serves as an interesting linguistic artifact.