An umbilical cord is the flexible tube that connects a developing baby to its mother before birth. Think of it as a lifeline: while the baby grows inside the mother's womb, the umbilical cord delivers oxygen and nutrients from the mother's blood to the baby, and carries away waste products the baby doesn't need.

The cord attaches to the baby at what becomes the belly button, or navel. After a baby is born and takes its first breath, doctors clamp and cut the umbilical cord because the baby no longer needs it. The small piece that remains dries up and falls off after a week or two, leaving behind the belly button.

The phrase cutting the umbilical cord has also come to mean breaking free from dependence on someone or something. When teenagers start making their own decisions and becoming more independent from their parents, people sometimes describe this as “cutting the umbilical cord.” Similarly, a new business might need to cut the umbilical cord from its parent company to operate on its own.