The correct spelling of the word "Diagometer" is "diagonometer." The IPA phonetic transcription of this word is /daɪˌæɡəˈnɒmɪtər/. The word is derived from the Greek word "diagnosis" meaning diagnosis and "metron" meaning measure. The diagonometer is an instrument used to measure the length and direction of diagonal lines or angles. It is commonly used in engineering and construction to ensure accurate measurements in building and designing structures.