# reflex

/ˈɹifɫɛks/ (US)

Source: https://englishreference.com/word/reflex
Updated: 2026-08-15

## Senses

### 1. automatic physical reaction

noun · CEFR B2

a physical movement that your body does automatically when something happens, without you thinking about it.

For teachers: an involuntary and nearly instantaneous movement in response to a stimulus, mediated by the nervous system without conscious thought.

- The doctor tapped my knee with a small hammer to check my reflexes.
- The patient exhibited a delayed reflex in the right leg, suggesting a potential issue with the lower spinal nerves.

### 2. historical language descendant

noun · CEFR C2 · Technical

a word or sound in a modern language that comes from an older version of that language.

For teachers: the linguistic descendant of a specific form or phoneme from a parent language in a daughter language.

- The English word 'father' is a reflex of an ancient Germanic word.
- Linguists traced the vowel shift by comparing the modern reflexes of the Proto-Indo-European root across several Romance languages.

### 3. reflection

noun · CEFR C2 · Literary

an image or light that is reflected off a surface.

For teachers: a reflection or an image produced by a reflection; specifically, light reflected from an illuminated surface onto one in shadow.

- The silver bowl showed a distorted reflex of the candles on the table.
- The painter captured the subtle reflex of the sunset on the underside of the bridge, illuminating the dark water below.

### 4. automatic

adjective · CEFR B2

happening automatically as a reaction to something.

For teachers: produced or performed involuntarily as a response to a stimulus.

- Blinking is a reflex action that protects your eyes from dust.
- The athlete's reflex response to the starting pistol was so fast it appeared almost anticipatory to the spectators.

### 5. geometry angle

adjective · CEFR C1 · Technical

describing an angle that is larger than 180 degrees but smaller than 360 degrees.

For teachers: denoting an angle that is greater than 180 degrees but less than 360 degrees.

- You need to measure the reflex angle on the outside of the triangle.
- To complete the calculation, the student had to subtract the interior angle from 360 to find the corresponding reflex angle.

## Examples

- The doctor tapped my knee to test my reflex.
- A goalkeeper needs incredibly fast reflexes to stop a ball traveling at high speed from such a short distance.
- While some behaviors are learned through years of repetition, the startle response remains a primitive reflex designed to protect the organism from sudden environmental threats.

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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.