Pickled cucumber

A pickled cucumber, most often simply called a pickle in the United States and Canada, is a cucumber that has been processed in a brine or vinegar solution and left to ferment for a period of time. Pickling is also used for many other things, such as onions, cabbage, and herring. One common type of pickle is the dill pickle. It is commonly used as a topping on meat products such as hamburgers, but can also be eaten on its own. It is often put on hamburgers or in hotdogs.

A deli pickle

A single sliced pickle.

The Simple English Wiktionary has a definition for: pickle.