membrane

membrane — noun

1. a thin, soft layer of tissue inside the body of a living thing that covers, line

1.nounB2
Definition

a thin, soft layer of tissue inside the body of a living thing that covers, lines, or connects internal organs and other structures.

Example

The mucous membrane inside your nose helps trap dust and germs before they reach the lungs.

mucous membrane — common compound noun for body linings

During surgery, the doctor carefully cut through a thin membrane to reach the damaged organ.

Common collocations
  • mucous membrane
  • thin membrane
  • membrane of the [organ]
  • connective membrane
  • membrane lining
Synonyms
  • tissue

    a broader term; tissue refers to any group of similar cells, not specifically a thin covering layer

  • lining

    refers specifically to the inner covering of an organ or cavity, narrower than membrane

  • layer

    a more general word; does not imply biological origin or thinness

Grammar Patterns

membrane + of + body part

adjective + membrane (mucous membrane, thin membrane)

Usage Note

Frequently modified by the name of the organ or body part it surrounds (e.g., mucous membrane, membrane of the brain). In medical contexts, many membranes have their own specialized names — pleura for the lung lining, peritoneum for the abdominal cavity, and meninges for the brain covering.

Common Mistakes

The membrane protects the body from the sun.
The skin protects the body from the sun.
Membrane refers to internal layers of tissue, not the outer skin.

2. a thin, flexible sheet of synthetic or natural material that separates two areas

2.nounB2
Definition

a thin, flexible sheet of synthetic or natural material that separates two areas, blocks the passage of liquids or gases, or serves as a cover for an opening.

Example

A waterproof membrane was installed beneath the roof tiles to keep rain from leaking in.

waterproof membrane — common collocation in construction

These running shoes use a breathable membrane that lets sweat escape while keeping water out.

breathable membrane — product feature collocation

Common collocations
  • waterproof membrane
  • breathable membrane
  • plastic membrane
  • synthetic membrane
  • membrane filter
Synonyms
  • film

    suggests a very thin layer, often transparent; common for packaging and coatings

  • sheet

    more general; does not imply flexibility or the function of blocking passage

  • barrier

    focuses on the function of blocking rather than the material itself

Grammar Patterns

adjective + membrane (waterproof membrane, synthetic membrane)

membrane + for + purpose

Usage Note

Often appears in technical contexts such as construction, engineering, and filtration. Common modifiers include waterproof, breathable, synthetic, and permeable. Unlike sense 1, this sense does not refer to living tissue.

Common Mistakes

She covered the table with a colourful membrane for the party.
She covered the table with a colourful tablecloth for the party.
Membrane is used for functional or technical coverings, not decorative ones.

3. the fine outer covering that surrounds every living cell, controlling which subs

3.nounC1
Definition

the fine outer covering that surrounds every living cell, controlling which substances are allowed to enter or leave.

Example

The cell membrane controls which nutrients enter the cell and which waste products leave.

cell membrane + control/allow/repair — typical verb patterns

Damage to the cell membrane can cause the cell to die because it can no longer hold its contents.

Common collocations
  • cell membrane
  • plasma membrane
  • membrane protein
  • membrane structure
  • outer membrane
Synonyms
  • plasma membrane

    a more technical synonym used in advanced biology; identical in meaning

  • outer membrane

    sometimes used for the outermost layer of a cell, especially in bacteria

Antonyms
  • cell wall

    a rigid outer layer found in plant cells, fungi, and bacteria — structurally different and not present in animal cells

Grammar Patterns

cell membrane

membrane + of + cell

Usage Note

Used almost exclusively in biology and life-science contexts. The compound noun cell membrane is a fixed term; advanced learners may also encounter the synonym plasma membrane. Distinguish from cell wall, which is a rigid outer layer found only in plants, fungi, and some bacteria.

Common Mistakes

The cell wall allows water to pass in and out of an animal cell.
The cell membrane allows water to pass in and out of an animal cell.
Only plant cells have a cell wall; animal cells are surrounded by a cell membrane.

Word family

  • membranous
    adjectiveC2
  • transmembrane
    adjectiveC2
  • intramembrane
    adjectiveC2

Synonym discussion

Sense: noun/1

Membrane, tissue, lining, and layer all refer to physical sheets or coverings, but they differ in specificity and scope. A membrane is always a thin, flexible sheet — either living (inside the body) or synthetic (a material barrier). Tissue is much broader: it describes any group of similar cells working together, such as muscle tissue or nerve tissue, and does not imply thinness or a covering function. Lining is narrower than membrane — it specifically refers to the inner covering of a hollow organ or cavity (e.g., the lining of the stomach). Layer is the most general term, used for any single thickness of material, from paint layers to skin layers. For example, you would say 'the membrane around the lungs' for a specific thin covering, but 'the tissue of the lungs' for the organ's substance, 'the lining of the stomach' for its inner surface, and 'a layer of fat' for a general stratified sheet.

membrane ↗tissue ↗lining ↗layer ↗

Common collocations

Phrases

  • thin membrane
  • outer membrane
  • flexible membrane

Prepositions

Etymology

LatinFrenchEnglish

Membrane comes from the Latin word membrāna, meaning 'thin skin' or 'parchment,' which itself comes from membrum, meaning 'limb' or 'body part.' The original sense was a thin layer covering a part of the body, and the word later extended to man-made thin sheets and the outer covering of cells.