a Christian bishop (=high-ranking priest) who lived in western Asia in the 4th century AD. He became connected with the custom of giving gifts to children either at Christmas (=in countries such as the UK and the US), or on the night before his saint's day (December 6th) (=in some countries, such as the Netherlands). The imaginary character Santa Claus is based on stories about him. He is also the patron saint of Russia.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
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