A LOT of people use the term “antipill” to refer to a particular type of heavyweight or high quality fleece – indicating that an “antipill fleece” will make a suitable pad backing. This is largely due to the way fabric retailers label their fabrics and customers recommending it under this name alone.
This is INCORRECT!
The term “antipill” actually means that the fabric will resist “pilling” – “pilling” is where the fabric gets worn and creates little balls of fluff (those are called “pills”) (See Wikipedia). That’s all. So an “anti-pill” fleece (or any other fabric) is simply one that is made to resist getting pilly.
LOTS of different fabrics are “antipill”. It probably indicates the fleece is a reasonable quality, but it has NOTHING WHATSOEVER to do with the thickness, density or durability of the fleece – it just means it will not get balls of fluff on it.
You can get very thin antipill microfleece right up to thick antipill polarfleece. “Antipill” does not mean the fleece is suitable as a waterproofing fabric.