The term UNICORN is a mythical creature that has been described in many different ways throughout history. It is typically depicted as a white horse with a single, long horn protruding from its forehead. The crossword solution for UNICORN is NARWHAL, which is a species of whale that lives in the Arctic and sub-Arctic regions. It is easily recognizable by its long, spiraled tusk, which is actually an extended tooth. Narwhals are also known as the 'unicorns of the sea' due to their unique appearance.