retard
In a technical or scientific context, this term describes the intentional slowing of a chemical reaction or physical process, such as using flame retardants to prevent the rapid spread of fire. It carries a neutral, functional connotation in engineering and chemistry. When used as a noun to describe a person, the word is highly offensive and derogatory. It has transitioned from a clinical medical term to a slur, and its use in social contexts is widely condemned as hate speech or extreme insensitivity.
Meanings
To delay or slow down the progress, development, or movement of something.
"The cold weather can retard the growth of the plants."
To make a process happen more slowly than it normally would.
"Certain chemicals are used to retard the spread of fire in building materials."
A person with an intellectual disability. (Note: This term is now widely considered offensive and derogatory).
"The term was once used in medical contexts but is now avoided."