Here's how it works:
* Verb: "chastise" means to punish or criticize someone severely.
* Past Participle: "chastised" is used to form verb tenses (e.g., "He had chastised the child") or as an adjective (e.g., "The chastised student sat quietly").
So, depending on how it's used in a sentence, "chastised" can function as part of a verb phrase or as an adjective.