Webbing is strong woven material made in long narrow bands, like a flat rope. You have touched it many times without knowing its name: the strap of a backpack, a seat belt, a luggage strap, a dog lead, a climbing sling, the flat straps under a sofa cushion that hold your weight up.

That last one is where the word started in furniture. Under the soft cushion of an old chair or bed, bands of webbing are stretched across the wooden frame in a criss-cross pattern, and they are what actually carry you. When an old sofa sags in the middle, the webbing underneath has stretched or snapped.

It is an uncountable noun, so say 'some webbing', 'a piece of webbing', 'two metres of webbing' — not 'two webbings'. Soldiers also use 'webbing' to mean the whole set of belts and straps they wear to carry equipment.

There is a second, quieter meaning: the skin between a duck's toes or between your own thumb and first finger can be called the webbing. Same picture, small scale.