The word "in goingest" is not a commonly used word. However, its spelling can be explained through the International Phonetic Alphabet (IPA) as follows: /ɪn ˈɡəʊɪŋɛst/. The first syllable, "in," is pronounced with a short "i" sound, while the second syllable, "going," is pronounced with a long "o" sound. The suffix "-est" indicates the superlative form, meaning "most in-going." This word can be used to describe someone who is the most inwardly focused or introspective.