A secret admirer is someone who has feelings for another person but does not reveal their identity. The term 'secret admirer' can be used to describe a person who admires someone from afar, or someone who sends anonymous gifts or messages to the object of their affection. The crossword solution for the term 'secret admirer' is 'SPY, ' which is a three-letter word. A SPY is someone who secretly collects information about an individual or organization without their knowledge.