This idiom describes something very common, inexpensive, or of little value due to its abundance. It suggests that the item or quality is so widespread that it lacks uniqueness or significance, often used to downplay importance or rarity.

The phrase is typically applied to objects, skills, or people in a dismissive or critical tone.

Originating in the United States in the early 19th century, the phrase reflects a time when a dime could buy a dozen (12) of something, like eggs or small goods, emphasizing cheapness. Early uses appear in 1830s newspapers, with an 1837 *New Orleans Picayune* article noting ‘oranges, a dime a dozen.’ By the late 19th century, it was applied metaphorically to people or qualities, as in ‘such workers are a dime a dozen.’ Its popularity grew in the 20th century, especially during the Great Depression, when abundance contrasted with economic scarcity.