a character in a children's Christmas song. Rudolph is a reindeer (=a large grass-eating wild animal with large horns) who has a shiny red nose. The other reindeer think his nose looks silly, but Santa Claus asks him to help the other reindeer to pull his sleigh on a foggy night, because his bright nose helps them to see where they are going.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
Dictionary pictures of the day
Do you know what each of these is called?
Click on any of the pictures above to find out what it is called.