Adjectives that start with S

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.

You are still if you are not moving. The two people in the picture are dressed up as statues and are being very still.

Something is strange if it is unusual and not what you would normally expect.
The opposite of strange is normal or ordinary.

The picture is of a very strange looking vegetable.

Strewn is a similar word to scattered. Things are strewn if they have been spread around with no particular pattern. The toys in the picture are strewn.

Someone is strong if they can lift or move very heavy things. An object is strong if it is hard to break. A color or a smell might be very strong if you can really notice it, more than ordinary colors or smells.
The man in the picture is very strong.

If someone calls you suave, it means that you are confident and charming. The opposite of suave is awkward.

Swarthy describes a man with dark hair and often a dark complexion.

A swift is a small, fast-flying bird with long, pointed wings. It lives in many parts of the world, often around cliffs or buildings where it can nest in sheltered spots. Swifts spend most of their time in the air, catching tiny insects while they fly.

Something is symmetric if it exhibits symmetry, that is if you draw a line down the middle of it, the two sides are mirror images of each other.