The phrase "hadst a part in" is an archaic form of "had a part in," meaning to have played a role in something. The spelling of "hadst" is pronounced /hædst/ in IPA phonetic transcription. The "st" at the end is an inflection used in Early Modern English to indicate second-person singular (you), similar to the use of "-est" and "-eth" with other verbs. Today, we use "had" as the standard past tense form of "have," without any inflection.
"Hadst a part in" is a phrase that can be understood by breaking it down into its individual components. The word "hadst" is the archaic second-person singular form of the verb "to have" in the past tense. It is derived from Middle English and was used during the period of Early Modern English. "A" is an article indicating one item or instance of something, and "part" refers to a portion, section, or role in a larger whole.
When combined, "hadst a part in" conveys that the subject (the person being addressed) possessed or possessed an involvement or role in something. The phrase implies active participation or connection to a particular event, situation, or venture in the past. "Hadst a part in" suggests that the individual had a share, contribution, or responsibility in relation to the subject under discussion.
It is likely to encounter this phrase in literary or historical contexts, as it reflects older forms of English. Usage of "hadst a part in" can be found in plays, poems, or texts written during the Early Modern English period, such as the works of William Shakespeare. In contemporary language, this phrase is rarely employed, as it has fallen out of favor in favor of modern verb tenses and phrasings.