They actually don't use these terms in the TV show. If they do, they're easy to miss considering how everyone, i mean EVERYONE, says "Walker" even if they aren't part of Ricks group. The only time I've heard them use anything but is that the people of Woodbury call them Biters. The comics, on the other hand, use these terms fairly often. Roamers being the most common. In fact, you rarely see the word "Walker" in the comics.

.....how, exactly? Wouldn't you be more likely to notice it if you had autism and less likely if you have ADHD, and you wouldn't even notice at all. Plus, it's one of those things that's so small that you don't even notice and just assume.
tl;dr don't be a ****

I'll be a **** if I damn well please you all can drown me in a sea of red thumbs. I really don't give a **** . It was VERY obvious to me. The Walking Dead is based on a world where the idea of zombies was never created they have no idea what they are so they have no choice but to create names for them.

tl;dr stfu