The word "hadst a lock on" is an archaic form of the phrase "had a lock on." The spelling of "hadst" is derived from the Old English second person singular past tense of "to have." The IPA phonetic transcription of "hadst" is /hædst/, with the "d" pronounced as a voiced dental plosive. The term "lock" in this context refers to a surety or guarantee. The phrase "had a lock on" means to have complete control or dominance over something.
Hadst a lock on is an archaic phrase that originated in Middle English, often associated with older texts or poetic language. The phrase combines two different words: "hadst" and "lock on." "Hadst" is the Old English second-person singular past tense of the verb "have," which means "to possess or own." In this context, it refers to "you had" or "thou hadst."
On the other hand, the term "lock on" describes the act of securely controlling or grasping a particular object, concept, or situation. The notion of "lock" implies a firm hold or control, akin to a key that opens or closes something. Consequently, when "hadst a lock on" is used in a phrase or sentence, it indicates that the subject (often implied as "you" or "thou") possessed complete control, understanding, or knowledge of a specific matter.
Thus, "hadst a lock on" can be defined as an archaic expression denoting the complete or firm possession of knowledge, understanding, or control over a particular subject. Though not commonly utilized in modern conversational English, it is occasionally encountered in classic literature, poetry, or historical texts, exemplifying a linguistic style and era different from current usage.