Definition: The word "petulant" is an adjective that describes someone who is easily irritated or annoyed, often in a childish or sulky manner. A petulant person might react with bad temper or impatience over small things.
Petulance (noun): The quality of being petulant.
Petulantly (adverb): In a petulant manner.
In summary, "petulant" describes a person who is easily annoyed and often displays childish behavior. You can use it to highlight immaturity in both children and adults.