Contrite is a formal adjective used to describe someone who feels regret for their bad behavior, or something, such as an apology, that shows such regret.

// Although the mayor appeared contrite about the most recent scandal plaguing city hall, many constituents remained unpersuaded.

Impunity, usually used in the phrase "with impunity," refers to exemption or freedom from punishment, harm, or loss.

// They mistakenly believe that they can break the camp's rules with impunity.

To rescind something, such as a law, contract, agreement, etc., is to end it officially. Rescind can also mean “to take back; to cancel.”

// Given the appeal court’s recent decision, it is likely that the law will be rescinded.

// The company later rescinded its offer.

Boffo is an informal word that describes things that are extremely good or successful.

// The most recent film in the long-running franchise has done boffo business at the box office, a testament to the series’ enduring popularity.

A simulacrum is a superficial likeness of something, usually as an imitation, copy, or representation. The plural of simulacrum is either simulacrums or simulacra.

// The surprise still succeeded, thanks to the simulacrum of confusion expressed by two guests when they were spotted before the big moment.

To procrastinate is to be slow or late about doing something that should be done, or about doing or attending to things in general.

// Tickets to the event are selling swiftly, so don't procrastinate—buy yours today.

// Not one to procrastinate, Harry set to work on the project immediately.

Antic refers to an attention-drawing, often wildly playful or funny act or action. It is usually used in its plural form, and is often used disapprovingly.

// It wasn't clear which students were ultimately responsible for the antics that unfolded in the cafeteria that day.

A cantankerous person is often angry and annoyed, and a cantankerous animal or thing is difficult or irritating to deal with.

// Although the former postman was regarded by some townspeople as a scowling, cantankerous old coot, he was beloved by neighborhood children, to whom he would regularly hand out butterscotch candies from his front stoop with a twinkle in his eye.

Yankee can refer broadly to anyone born or living in the U.S., more narrowly to only those in the northern U.S., or even more narrowly to only those in the states of New England.

The broadest use is especially common outside the U.S.

// It took the children some time to adjust to being the only Southerners in a classroom full of Yankees.

// After years of international travel, he'd grown accustomed to living as a Yankee abroad.