珍しい (mezurashii) means "unusual," "rare," or "uncommon." You use it to describe something that doesn't happen often, or something that is not commonly seen or found. It often implies a sense of surprise or uniqueness. For example, 「これは珍しい花です。」 (This is a rare flower.)

滅多にないこと、あまり見かけないことを言います。普通ではないことに使います。「これは珍しい花です。」