Where else?

[Little Rik]

Remember that so far there is no single universally agreed scientific meaning of the word "matter".

This is true, to an extent.
However, it IS universally agreed that water and air are matter.

Water is 2 parts hydrogen to 1 part oxygen.
"Air" technically isn't a thing. It's what we basically call our atmosphere, which is... 78% nitrogen, 21% oxygen, 1% argon, and then trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, and ammonia.
I hate to inform you but all those elements and compounds listed, are matter.

Sure, sure.  

But in this way we can also say that the milk, water, air and whatever else you may like to include is cheese.
Isn't that a stupid way to put it?