sheath

American  

[sheeth] / ʃiθ /

noun

• sheaths
  plural

1. a case or covering for the blade of a sword, dagger, or the like.

2. any similar close-fitting covering or case.

3. a condom.

4. Biology. a closely enveloping part or structure, as in an animal or plant.

5. Botany. the leaf base when it forms a vertical coating surrounding the stem.

6. a close-fitting dress, skirt, or coat, especially an unbelted dress with a straight drape.

7. Electricity. the metal covering of a cable.

8. Electronics.

   1. the metal wall of a wave guide.

   2. a space charge formed by ions near an electrode in a tube containing low-pressure gas.

   3. the region of a space charge in a cathode-ray tube.

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verb (used with object)

1. to sheathe.

sheath British  

/ ʃiːθ /

noun

1. a case or covering for the blade of a knife, sword, etc

2. any similar close-fitting case

3. biology an enclosing or protective structure, such as a leaf base encasing the stem of a plant

4. the protective covering on an electric cable

5. a figure-hugging dress with a narrow tapering skirt

6. another name for condom

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verb

1. (tr) another word for sheathe

sheath Scientific  

/ shēth /

1. An enveloping tubular structure, such as the base of a grass leaf that surrounds the stem or the tissue that encloses a muscle or nerve fiber.

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Other Word Forms

Derived Forms

• sheathless
  adjective
• sheathlike
  adjective
• sheathy
  adjective

Inflected Forms

Nouns

• sheaths
  plural

Etymology

Origin of sheath

before 950; Middle English s ( c ) heth ( e ), Old English scēath; cognate with German Scheide; see shed ²

Explanation

A sheath is a protective case for a knife or a sword. The most exciting part of a staged sword fight might be the moment when the hero pulls his weapon out of its sheath. A sheath is also a dress that is straight, fitted, and simple. You might advise your Aunt Martha to choose a sheath dress for her third wedding, instead of the white lace gown with the long train. The word sheath most likely comes from the Old English scēath, meaning a divide or a split, like the split piece of wood which originally served as a sword's sheath.

Example Sentences

See Examples For:

sheath sheaths

Clough said the small skipper needed grass left uncut throughout the year, "because the tiny caterpillar spends the winter inside a grass sheath".

From BBC ● Jul. 23, 2026

"The crystallisation basins are covered by grass and sheath and so on. This is not the landscape that usually salinas are," she said, explaining the changes to the area that saltwork pumping created.

From Barron's ● Jul. 15, 2026

The myelin sheath is a protective coating that surrounds nerve fibers in the brain and spinal cord.

From Science Daily ● Apr. 15, 2026

Calvin Klein, where Bessette worked before marrying JFK Jr., has a “90s Edit” on its website showcasing sheath dresses, white button-down shirts and other minimalist looks from the era.

From The Wall Street Journal ● Apr. 7, 2026

He took a step toward Jeanne and pulled the sword from its leather sheath.

From "The Inquisitor's Tale" by Adam Gidwitz

Standard CD20 antibodies are an established treatment for MS, with the antibodies targeting the renegade autoimmune cells that damage nerve sheaths.

From Barron's ● Jun. 3, 2026

It requires a level of physical brain development called mylenation — the growth of fatty sheaths that wrap around nerve cells, insulating them and allowing information to travel more quickly and efficiently through the brain.

From Los Angeles Times ● Jun. 24, 2025

The extraordinary darkness that sheaths the Atacama, which stretches for hundreds of miles in Chile’s north, has made it a haven for astronomers searching for planets and stars shimmering in the night sky.

From Salon ● Apr. 28, 2024

The delicate tissue sheaths that insulate each biological circuit lay in “disorganized clumps,” and throughout Mr. Card’s brain there was scarring and inflammation suggesting repeated trauma.

From New York Times ● Mar. 6, 2024

She pulled blades of grass from their sheaths and ate the sweet ends.

From "Julie of the Wolves" by Jean Craighead George

Related Words

• covering