# nebula

/ˈnɛbjəɫə/ (US) · /nˈɛbjʊlɐ/ (UK)

Source: https://englishreference.com/word/nebula
Updated: 2026-08-27

## Senses

### 1. space cloud

noun · CEFR B2 · Technical

a huge cloud of gas and dust in space, which can look like a bright or dark patch in the sky.

For teachers: an interstellar cloud of dust, hydrogen, helium and other ionized gases.

- The Orion Nebula is one of the brightest objects you can see in the night sky.
- Astronomers used the infrared telescope to peer through the thick dust of the nebula, revealing the birth of several new stars within its core.

Usage: The plural form can be either 'nebulas' or 'nebulae'.

### 2. eye condition

noun · CEFR C2 · Archaic · Technical

a faint, cloudy spot on the clear front part of the eye.

For teachers: a slight opacity or white spot on the cornea, typically resulting from injury or infection.

- The old medical book described a nebula that partially blocked the patient's vision.
- The physician noted a faint nebula on the left cornea, though it appeared to be a stable scar rather than an active infection.

Teaching tip: This sense is rarely encountered outside of historical medical texts; modern practitioners use more specific clinical terms for corneal scarring.

## Examples

- The Orion Nebula is visible through a small telescope.
- Astronomers use powerful infrared cameras to peer through the thick dust of the nebula and see the stars forming inside.
- The spectacular colors observed in a planetary nebula are produced by the ionization of different gases as they are heated by the intense radiation of a central white dwarf.

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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.