What part of speech is “bought”

bought is a past tense of the verb 'buy,' which is used to describe an action that has already taken place. It is typically placed after an auxiliary verb like 'have' or 'had.' It functions as a way in which to talk about the past, and is often utilized to create a sense of completion.

1. I have bought a new car.

2. He had bought the tickets ahead of time.

3. They had bought the necessary supplies for the party.