What is a goblin?

Goblin: The term goblin is a collective noun for evil spirits like redcaps and bugbears. They are usually grotesque and misshapen but are of human form. They live in dark places and are of a very mischievous nature. It is said that their smile curdles the blood and that their laugh causes milk to sour and causes fruit to fall off trees. Typically, they only cause slight inconveniences like nightmares, but at times they can be very dangerous.

In Lord of the Rings, a goblin is a degenerate orc. However, the two terms are used interchangeably, but orcs that live in the mountains are usually referred to as goblins.

The Hobbit describes them as "cruel, wicked, and bad-hearted. . . . they are usually untidy and dirty." It also noted that goblins go faster than dwarves.