sheath

American  

[sheeth] / ʃiθ /

noun

plural

sheaths

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

• sheathless
  adjective
• sheathlike
  adjective
• sheathy
  adjective

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

To test this idea, Zhang and his team examined whether the mutation could protect the myelin sheath.

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

Mr Rowe was carrying a Japanese-made trowel in its sheath, a small Japanese gardener's sickle and a peeling knife, along with a trug of vegetables.

From BBC • Aug. 6, 2025

Frankly, Aidan’s behavior is far more concerning than Wyatt’s, a flag so big and red that Carrie could make a stunning sheath dress out of it.

From Los Angeles Times • Jul. 3, 2025

Threading the dagger and sheath along the strap, he fastened it around Sam’s waist.

From "Redwall" by Brian Jacques

Related Words

• covering