noun

• (US) A television program shown after its initial presentation, particularly many weeks after its initial presentation; a repeat.
  "I'm not a fan of the new Simpsons episodes, but the old reruns have me in stitches, although I've seen them countless times."
• (publishing) Another printing run (impression; batch of copies of a given edition) of a book, cartoon, etc.
• (politics) A political candidate who holds the same political agenda or doctrine as a past or incumbent holder of a given political office.
• (computing) A second or subsequent run of a computer program.
  "Each rerun of the algorithm takes several minutes."

verb

• (transitive) To run again; to repeat.
  "Ms. Hill has rerun those questions in her mind. “If the girls told me they want to stay where they are, I would have to leave them,” she said."
• (transitive) To broadcast (a television program etc.) again.
  "They're still rerunning The Flintstones on this channel."
• (intransitive) To be broadcast again.
  "Everyone is talking about Lemonade, Beyoncé's new visual album that immediately became a sensation when it debuted on HBO on Saturday night. For those who missed it (and those without a loved one's HBO Go password), Lemonade even reran just before the Game of Thrones' highly anticipated season six premiere on April 24."
• (transitive) To run (a race or other contest) again.
  "rerun the election"