The quality of being soft and able to be pressed or squeezed down.
Squashiness is usually a good thing, like when you hug a soft pillow.
Examples:
I like the squashiness of this pillow.
The squashiness of the mud made it hard to walk through.
She enjoys the squashiness of the marshmallows in her hot chocolate.
The squashiness of the playdough makes it fun to play with.
The squashiness of the mattress made it feel like sleeping on a cloud.
The squashiness of the teddy bear made it perfect for hugging.