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

Etymology

Origin of membrane

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

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 study, published in Nature Cell Biology, is titled "Leucine inhibits degradation of outer mitochondrial membrane proteins to adapt mitochondrial respiration."

From Science Daily ● Oct. 3, 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

To explain the pattern, the researchers built mathematical models of the membrane surrounding an axon.

From Science Daily ● Sep. 17, 2026

"They help maintain cell membrane integrity, store energy, and support essential signaling processes in the body."

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

The oldest resurrected antimicrobial peptides were able to disrupt bacterial membranes, but the bacteria apparently repaired the damage and survived exposure to the peptides.

From Science Daily ● Sep. 28, 2026

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

From The Wall Street Journal ● Sep. 19, 2026

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

From The Wall Street Journal ● Sep. 19, 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

He heard the eyases chittering, saw Frightful sitting erect on her stub, and let his nictitating membranes slip across each eye.

From "Frightful's Mountain" by Jean Craighead George

Related Words

• sheath
• sheet