The correct spelling of the term "wast tense" is actually "past tense". It is a grammatical term used to refer to the tense used in describing actions or events that have already occurred. The spelling of "wast" is an archaic form that was used in Old English. The correct pronunciation of "past tense" in IPA phonetic transcription is /pæst tɛns/. In modern English, the spelling and pronunciation of "past tense" have evolved from its earlier form.