She has to be the appropriate size and shape or the nightie wouldn't fit.

As for how all those odd names and shapes fit together.

The metal ion is usually located in a pocket whose shape fits the substrate.

Where shapes don't fit, other shapes might be found.

Take a picture of a bear and maybe draw over it so you can see what shapes would fit into it!

But the eye is deceived: this shape will fit into the gap nicely.

One way to classify shapes is to describe a bigger shape that the shape fits inside of.

For example, two-dimensional shapes like circles will fit inside of a flat plane.

These shapes fit together to tile a plane, yet they can have five and ten-fold symmetry.

The shapes of these continents nearly fits together.