fraenum

/ˈfriːnəm/
noun
  1. A small fold of skin or tissue that holds a body part in place, such as the one under the tongue or inside the upper lip.
    • The dentist noticed the fraenum inside her upper lip was attached unusually low.
    • The doctor checked the baby's fraenum under the tongue to see if it was too tight.
    • Some people have a short fraenum that can make it hard to speak clearly.
Synonyms