No, but anyone who has used the tube or busses more than a couple of times will know exactly what they're talking about when they see the pictures of the seats associated with the word.

Check out Geoff Marshall's video with a real life Tube moquette designer (Paul Marchant):

https://www.youtube.com/watch?v=cAJrfL6loC8

I can't remember a time when I didn't know the word, but then I grew up near London so used the Tube regularly as a child.

It's that disgusting fabric found on the Tube that when you slap it, you can see a plume of dust and god knows what else