https://www.gosh.nhs.uk/conditions-and-treatments/health-dictionary/health-dictionary-f/
Health dictionary - F
Faeces
The medical word for poo. Once all the water and goodness has been absorbed from what you eat, faeces is all that’s left.
Failure to thrive
The diagnosis often given to babies and children who are not getting enough nutrition from their food. This could be due to not eating enough or in some cases, to the goodness in food not being absorbed properly by the intestines.
Fainting
Temporary loss of consciousness due to a lack of oxygen in the brain. If you feel faint, you should sit down and lean forwards, with your head between your knees. This will encourage blood to flow towards your brain.
Fasting
Not eating or drinking. Some people fast for religious reasons. In hospital, you have to fast for a certain amount of time before an anaesthetic.
Femur
The medical word for thighbone – the longest bone in your body. The top of the thighbone connects with your hip in a ‘ball and socket’ joint and the bottom connects with your knee in a ‘hinge’ joint.
Fetus
A baby developing in the womb. Before the eighth week, the baby is called an embryo. While the baby is developing in the womb, it will grow from about 2.5cm long to a final length of 51cm long.
Fibula
One of the bones in your lower leg. The fibula is much thinner than your shinbone (tibia) and doesn’t connect with your knee. Instead it forms part of your ankle. Its main purpose is to give the muscles a place to connect.
Fistula
This is an abnormal connection (or hole) that happens between an organ, vessel, skin or intestine. They can occur as a result of injury, surgery or infection.
Fixator
The name for a device that holds together a bone by pins that are inserted through the skin into the bone and held in place by a surrounding brace. It can help a broken bone to heal correctly but can also be used to lengthen a bone by gradually pulling the cut ends of the bone apart so that new bone forms in the gap.
Foot
Your foot is made up of 26 bones by the time you’re an adult and the largest one is your heel bone. Your feet are important because they help you stand and walk upright and they’re also vital for walking.
Foreign body
Anything that is in your body, either inside or in one of the openings, that shouldn’t be there is called a foreign body. Choking is usually caused by a foreign body. You should never try to remove a foreign body yourself – this is a job for experts!
Fracture
When you break a bone in your body, it’s called a fracture. There are lots of different types of fracture – some are simple fractures where the bone breaks but doesn’t come through your skin, but others are complicated fractures which need to be pinned together to make them heal properly.
Freckles
Freckles are just small patches of skin containing melanin or pigment, the substance that gives us colour. Freckles usually appear when you’re out in the sun. People with fair or red hair tend to have more freckles than dark haired people, and so should take care not to burn by using a sun block cream.