membrane

American  

[mem-brayn] / ˈmɛm breɪn /

noun

• membranes
  plural

1. Anatomy. a thin, pliable sheet or layer of animal or vegetable tissue, serving to line an organ, connect parts, etc.

2. Cell Biology. the thin, limiting covering of a cell or cell part.

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membrane British  

/ ˈmɛmbreɪn /

noun

1. any thin pliable sheet of material

2. a pliable sheetlike usually fibrous tissue that covers, lines, or connects plant and animal organs or cells

3. biology a double layer of lipid, containing some proteins, that surrounds biological cells and some of their internal structures

4. physics a two-dimensional entity postulated as a fundamental constituent of matter in superstring theories of particle physics

5. a skin of parchment forming part of a roll

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membrane Scientific  

/ mĕm′brān′ /

1. A thin, flexible layer of tissue that covers, lines, separates, or connects cells or parts of an organism. Membranes are usually made of layers of phospholipids containing suspended protein molecules and are permeable to water and fat-soluble substances.

2. See cell membrane

3. Chemistry A thin sheet of natural or synthetic material that is permeable to substances in solution.

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Other Word Forms

Derived Forms

• intermembrane
  adjective
• membraneless
  adjective

Inflected Forms

Nouns

• membranes
  plural

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Etymology

Origin of membrane

1375–1425; late Middle English; Middle English membraan parchment < Latin membrāna. See member, -an

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Explanation

A membrane is a thin layer of something. For an example of a membrane, you don’t have to look far: your skin is a kind of membrane. Membranes are thin and flexible, but usually still strong enough to protect what’s inside or underneath them. Biologists often study membranes, such as those that surround your cells and organs. There are also membranes that don’t have anything to do with biology. A high-tech jacket might have a waterproof membrane to keep you dry in the rain.

Example Sentences

See Examples For:

membrane membranes

The MAL gene produces a small membrane protein called Mal.

From Science Daily ● Sep. 19, 2026

Alongside the pearled axons, they found evidence of ultrafast endocytosis, a process through which nerve endings quickly retrieve membrane after releasing chemical messages.

From Science Daily ● Sep. 17, 2026

The human study primarily investigated membrane recycling at synapses.

From Science Daily ● Sep. 17, 2026

The researchers combined electrical stimulation with rapid freezing to capture tiny membrane changes in mouse and human brain slices.

From Science Daily ● Sep. 17, 2026

Pterodactyls had wings formed by a thin skin and muscle membrane stretching from one of their elongated fingers to their hind limbs.

From "Mr. Lemoncello's Library Olympics" by Chris Grabenstein

In the 1980s, freezes ruptured oranges’ cell membranes and turned new growth black.

From The Wall Street Journal ● Sep. 19, 2026

Think mushroom leather, spider-silk filaments, membranes of algae.

From The Wall Street Journal ● Sep. 19, 2026

Instead, larvae can enter wounds or mucous membranes, where they must be removed quickly to limit further damage to the surrounding tissue.

From Science Daily ● Sep. 15, 2026

Meningitis is an infection and swelling of the fluid and membranes around the brain and spinal cord, according to the Mayo Clinic.

From Los Angeles Times ● Aug. 27, 2026

To stay alive, you have to be able to hold out against equilibrium, maintain imbalance, bank against entropy, and you can only transact this business with membranes in our kind of world.

From "The Lives of a Cell" by Lewis Thomas

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Related Words

• sheath
• sheet

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