Most commonly, the highly sensitive part of the penis, where the foreskin connects with the glans, just below the opening of the urethra. The area remains sensitive in those who are circumcised. Frenulum generally refers to a small piece of tissue that connects body parts or holds one in place. Thus, the frenulum of the tongue is the tissue at the base of the tongue that attaches it to the floor of the mouth. Other body parts, including the labia minora, the clitoris, and the upper and lower lips (of the mouth) also have frenula.