The clirotis is an organ. The homolog of the male penis, it engorges during the arousal phase. There are other organs like the clitoris that arouse, the labia arouse, the opening to the vagina called the vestibule arouses. The opening where the urination comes through, there is a urethral glands area that arouses. There's many arousing tissues, in a woman's genitalia. And the clitoris, being a very important one, is yet another example.