Medical

A shell is the hard outside coating found on many animals. Snails have shells that form a spiral that was built up as the snail grew bigger. crabs and turtles have a hard shell that perfectly fits the animal inside. Most animals that have shells can hide inside them if they are scared.

Your shoulder is the joint between your arm and your body. People sometimes tap you on the shoulder to get your attention. The woman in the picture has a rat on her shoulder.

You see with your eyes. Sight is one of the most important senses. Someone who cannot see is blind. If you can't see properly, you probably need glasses.

Your skin is the largest organ on your body. It covers you completely and protects your muscles and other organs. Your skin has glands on it that produce oil and sweat, and your skin has follicles in it that grow hairs.

A sling is a kind of bandage, usually for supporting a sprained or broken arm.

A sneeze is a sudden explosion of air from your nose and mouth. You usually sneeze if something tickles the inside of your nose, or if you have a cold.
It is a good idea to cover your nose and mouth when you sneeze, like the man in the picture. A lot of mucous can come out when you sneeze and can travel a long way. If you are sick, you can make other people sick by sneezing near them.

Snuff is powdered tobacco leaves, designed to be sniffed through the nose. Snuff was much more popular in the past than it is today. Most people today smoke cigarettes rather than sniff tobacco.
Snuff was carried around by people in their pockets in small, airtight snuff boxes, which ranged from simple wooden boxes like in the picture to quite elaborate and expensive jewelled boxes.

Your spine, or vertebral column is the row of bones that runs along the centre of your back. Your spine is made of lots of small bones called vertebra.

A splinter is a tiny piece of wood that is sharp at one end. You can get splinters in your hands if you work with splintery wood without gloves on.

A plant or animal is sterile if it cannot produce offspring. Something that has no living things on it or that cannot sustain living things is also called sterile. Medical equipment is usually provided in sealed packets that keep it sterile.
Another word for sterile is barren. The opposite of sterile is fertile.