Mígrannen in Sindarin means ‘Grey Pilgrim’, so that could be one of the reasons.
Some have suggested he was called Mithrandir because he had a big grey beard and hair, which matches with his house color of grey. Others have speculated that his name literally means “the Grey Wanderer.” But it’s most likely a combination all three factors were combined to come up with Gandalf’s full name.
And there you go – thanks for reading! Hope you enjoyed learning more about your favorite characters from The Lord of the Rings world! Good luck on all your quizzes and tests!