The spelling of the words "hadst a seat" is a little unconventional. The word "hadst" is an archaic form of the word "had" in the second person singular past tense, which was commonly used in Shakespearean English. The IPA phonetic transcription for "hadst" is /hædst/. "A" is a common indefinite article, and "seat" refers to a place to sit. Despite its unconventional spelling, "hadst a seat" is a simple phrase with a clear meaning.