Sizes

Broad is another word for wide. The man in the picture has a broad chest.

A dwarf is a small person, born with a condition that makes them unusually small. Most dwarves have short arms and legs and facial features that are distinctive.
A dwarf of any kind of plant or animal is a smaller variety of that plant or animal. Dwarf forms of animals are often kept as pets.

Gigantic is another word for huge.

Large is another word for big. The cat in the picture is large.

Something is long if it goes for a considerable way in one direction. Something goes for a long time if it happens for an extended period.
The lizard in the picture has a very long tail.
The opposite of long is short.

Medium is a way to describe something that is a size in between small and large.

A gap between two things is narrow if the two things are quite close together and there is not a lot of room between them. The street in the picture is very narrow. The opposite of narrow is wide.

Something is short if the highest part of it is much lower than the top of similar things. The woman in the picture is much shorter than the man in the picture. The opposite of short is tall.

Something is tall if the top of it is much higher up than the top of similar things. The person wearing the scarf on the left of the picture is taller than the other person in the picture. Giraffes and basketball players are tall.

The opposite of tall is short.

Something is thin if there is a very short distance from one side of it to the other. For example, thin ice is ice that would not be strong enough to stand on. The bird in the picture has very thin legs. Another word for thin is skinny. The opposite of thin is fat or thick.