A biopic is a film that tells the story of a real person’s life — often a singer, an actor, a leader, or a sportsperson. People who write about movies use this word all the time. It is a little informal, but not slang; you can put it in a review. Say “a biopic of Mandela” or “they are making a biopic about her.” Though actually, a biopic is not a documentary. A documentary tries to show real film and real talk. A biopic hires actors, writes scenes, and often changes time, talk, and even facts to make a good story. So “based on a true story” is a softer promise than “this is exactly what happened.” If you want the tidy historical record, a book is safer; if you want the feeling of a life, people still flock to biopics. The word is a shortened form of biographical picture: bio from the life-story side, pic from picture, here meaning a film.