# retarded

/ɹiˈtɑɹdəd/ (US) · /ɹɪtˈɑːdɪd/ (UK)

Source: https://englishreference.com/word/retarded
Updated: 2026-08-08

## Senses

### 1. physics/engineering

adjective · CEFR C2 · Technical

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

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

- The scientist calculated the retarded potential of the electromagnetic wave.
- 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.

### 3. delayed development

adjective · CEFR C1 · Formal

slowed down or held back in growth or progress.

For teachers: characterized by a delay in development, growth, or progress.

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

## Examples

- The chemical reaction was retarded by the addition of a cooling agent.
- The engineers noted that the flow of water was retarded by the narrow pipes, causing a significant drop in pressure.
- In certain physical systems, the retarded potential accounts for the time delay required for a signal to travel from the source to a distant observer at the speed of light.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.