English Reference
adjective

retarded

adj.
US /ɹiˈtɑɹdəd/ UK /ɹɪtˈɑːdɪd/ re·tard·ed

  1. 01 C2 Proficiency Technical Science

    describes a signal or force that is delayed because it takes time to travel.

    designating a parameter, such as an electromagnetic field, that is adjusted to account for the finite speed of propagation.

    Simple

    The scientist calculated the retarded potential of the electromagnetic wave.

    In context

    In electrodynamics, the retarded time accounts for the interval required for an effect to propagate from the source to the observer at the speed of light.

    Usage

    Used almost exclusively in specialized physics contexts regarding wave propagation.

  2. 02 C1 Advanced Formal

    slowed down or held back in growth or progress.

    characterized by a delay in development, growth, or progress.

    Simple

    The cold weather resulted in the retarded growth of the garden crops.

    In context

    Economic recovery was retarded by the sudden collapse of the regional banking sector and subsequent lack of credit.

    Usage

    In modern contexts, this sense is usually applied to inanimate objects or abstract processes like 'growth' or 'progress'.

He’s now not only out of the game, but has apparently been described by Trump, variously, as weak, confused, dumb, an idiot, a disgrace, and “mentally retarded”.

The Guardian· 5 Sept 2026

After that, Yiannopoulos returned to the platform with a series of inflammatory posts, including one that called the “Muslim world functionally retarded”.

Al Jazeera· 28 Aug 2026

From retard + -ed.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level C2 · Proficiency
Frequency Frequent
Updated