Use the word eatery when you're talking about a cafe or restaurant. You might stop at a great local eatery for a burger after seeing a movie.
Eatery is a casual or informal word for a place to buy and eat prepared food. A diner is one kind of eatery, and a Chinese restaurant is another. You might have a favorite eatery among all the choices on a college campus, or know of an all-night eatery where you can get a snack at three a.m. Eatery was first used right around 1901, from eat, with its Old English root of etan, "to eat, devour, or consume."