The term "mentally retarded" is an outdated and considered offensive way to describe individuals with intellectual disabilities. It was used in the past to refer to people who have below-average cognitive abilities, which can affect their learning, problem-solving, and overall functioning in society.
In academic or professional settings, you might encounter terms like "cognitive impairment" or "developmental delay," which are used to describe similar conditions but in a more respectful and precise way.
While "retarded" can also mean "delayed" in a general sense (like a delayed train), it is important not to use it to describe people as it can be considered offensive.
There aren’t specific idioms or phrasal verbs directly related to this term. However, it is important to approach discussions about disabilities with sensitivity.
The term "mentally retarded" is no longer acceptable.