The Grammar Opera?

[thejessecougar]

The internet came in handy today after a work discussion about why our letter-size legal pads were called legal pads if they are not legal size, which led to a discussion about what the word is when a product name or attribute becomes the name of the item itself.

I ended up rooting around and finding antonomasia and someone else pointed out that coinage is also appropriate.

I couldn't remember if S&W had a section on such terms as well so when I went to that wiki I found:
Strunk & White, the Opera Cycle