Over time, it began to be used to describe people with intellectual disabilities. This usage evolved from the idea that individuals with intellectual disabilities had "slowed" development compared to others.
However, it's important to note that the term "retarded" has become deeply offensive and stigmatizing. It's no longer considered appropriate or respectful to use this word to describe people with intellectual disabilities.
Instead, it's crucial to use respectful and accurate terminology like "person with an intellectual disability" or "individual with developmental delays."