Used originally for people using the website goeyeball.com to price monitor items and save money during the recession of 2009. A more broad definition as someone who knows how to save and keeps an eye on sales.
banking term; used to describe a situation where you make a guestimate by looking at it (eg. a stack of change or wad of bills) and being precise about the amount.
Dude! That's $536.78.. whoa, I'm right! I totally eyeballed it!!!
The creature known as the intersection eyeballer is the person opposite of you at a two, three, or four way stop sign who, regardless of coming to a complete stop several seconds before you, looks you up and down for some time until you cannot handle it anymore and proceed to drive out of turn.
Whoa that SUV has been at the other end of the intersection for quite some time. This is pretty close to a stop sign standoff except he's staring me pretty hard. Let's cut this intersection eyeballer off and get out of here