# mucus

/ˈmjukəs/ (US) · /mjˈuːkəs/ (UK)

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

## Senses

### 1. bodily secretion

noun · CEFR B2 · Technical

the slippery liquid made by your body to protect your nose, throat, and stomach.

For teachers: a viscid secretion produced by the mucous membranes, consisting of water, mucins, and inorganic salts, which serves to lubricate and protect tissues.

- When you have a cold, your body produces more mucus to help fight the infection.
- The respiratory system relies on a thin layer of mucus to trap inhaled particles and pathogens before they can reach the lungs.

Usage: Uncountable in general usage; plural 'mucuses' is rare and restricted to medical contexts describing different types.

Teaching tip: Learners often confuse the spelling of the noun 'mucus' with the adjective 'mucous'. Point out that the -ous ending is a common adjective marker in English.

### 2. plant substance

noun · CEFR C1 · Technical

a sticky substance found in some plants that helps them hold water.

For teachers: a gelatinous substance found in certain plants, often referred to as mucilage, which aids in water retention.

- The thick mucus inside the aloe vera leaf is used to soothe burnt skin.
- Botanists observed that the desert plant secreted a thick mucus to prevent dehydration during the peak of the dry season.

Usage: Often used interchangeably with 'mucilage' in botanical descriptions.

Teaching tip: This sense is quite specialized; for general purposes, 'sap' or 'gel' is more common when talking about plants.

## Examples

- Mucus helps protect your lungs from dust.
- When you have a cold, your body produces extra mucus to help trap and remove germs from your system.
- The respiratory system relies on a thin layer of mucus to capture inhaled particulates, which are then cleared by the rhythmic beating of microscopic cilia.

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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.