retard

Derived from the Latin retardare, meaning "to make slow, delay, keep back, or hinder," the term entered English initially as a verb used in mechanics and physics. In the medical field during the early 20th century, "mental retardation" was introduced as a neutral clinical diagnosis to replace older terms like "idiot" and "imbecile," which had fallen into pejorative use. Over the following decades, the noun form evolved into a common slang insult.

Usage of the term is highly contested and heavily dependent on context. In technical fields such as automotive engineering, aviation, and music, the word remains standard and non-offensive when referring to the slowing of a mechanism or tempo (e.g., "retarding the timing"). However, when applied to people, it is widely classified as a slur (often referred to as "the r-word"). Disability advocates argue that using the term—even as a synonym for "foolish"—dehumanizes people with intellectual disabilities and reinforces exclusion. While some speakers maintain they use the word without intending to reference disability, major organizations like the Special Olympics have campaigned successfully to remove the term from medical and legal classifications in favor of "intellectual disability."

Example:
"The chemical agent was added to the mixture to retard the spread of the fire."

Example:
"Most style guides now advise against using the word retard as an insult due to its derogatory history regarding the disabled community."