Longman Dictionary of Contemporary English
Wiktionary
n. (context idiomatic English) An inexpensive diner or other informal restaurant, especially one specializing in frying or grilling.
WordNet
n. a small restaurant specializing in short-order fried foods
Wikipedia
Greasy spoon is a colloquial term for a small, cheap restaurant or diner typically specialising in fried foods. According to the Oxford English Dictionary, the term originated in the United States and is now used in various English-speaking countries. Originally disparaging, the term is now more frequently used in an endearing sense.
The name "greasy spoon" is a reference both to the typically high-fat, high-calorie menu items at such places, for example eggs and bacon, and to the supposed general standard of cleanliness. The term has been used to refer to a "small cheap restaurant" since at least the 1920s.
Usage examples of "greasy spoon".
After some casting about and a few false leads, we settled for a greasy spoon of sorts on Davenport, with vinyl seats and jukeboxes at the tables, stocked with country music and a sprinkling of old Beatles and Elvis Presley songs.
They would establish the Greasy Spoon here, a few blocks away from the naval base.
The Arab and the Jew that runs that peacenik greasy spoon, it's their own people that wants it shut down the most.
It had been started by a man attacking another man with a knife in a dice game in a room back of a greasy spoon restaurant.
Svobodov, this close, sort of creaked when he walked, and that was the armor under his shirt that Rydell had noticed before, back in that greasy spoon.
Here I was in the Tokyo version of a greasy spoon, surrounded by a mob of tough-looking bastards in dripping boots and the requisite New York-style rude waitress, and the food was on a par with the best of my hometown: fresh, clean, beautifully, if simply, presented.
Philosophers should wash dishes in a greasy spoon two nights out of ten.