challenge – v. to invite someone to take part in a competition; to compete against an opponent

character – n. a person in a play, movie or television show

formal – adj. done in an official way; relating to an important or ceremonial event

casual – adj. unofficial; done without much thought

topic – n. subject

etymology – n. an explanation of where a word came from : the history of a word

stoicism – n. the quality or behavior of a person who accepts what happens without protesting or showing emotion

introduce – v. to bring into use or operation; to make someone known to another person

grammar – n. the system and structure of a language

dad – n. someone's father