The correct spelling of the word under signing is "undersigning." This word is spelled with the prefix "under" and the verb "signing." The IPA phonetic transcription of this word is /ʌndərˈsaɪnɪŋ/. The first syllable is pronounced with a short "u" sound, followed by a schwa sound. The second syllable is stressed and pronounced with the "ai" diphthong. The final syllable is pronounced with the "ing" suffix and a short "i" sound. Correct spelling and pronunciation are important for clear communication in all types of settings.