sheath

noun

ˈshēth 

plural sheaths ˈshēt͟hz  ˈshēths 

1

: a case for a blade (as of a knife)

2

: an investing cover or case of a plant or animal body or body part: such as

a

: the tubular fold of skin into which the penis of many mammals is retracted

b(1)

: the lower part of a leaf when surrounding the stem

(2)

: an ensheathing spathe

3

: any of various covering or supporting structures that resemble in appearance or function the sheath of a blade: such as

a

: sheathing sense 2

b

: a woman's close-fitting dress that is usually worn without a belt

c

British : condom sense 1

Synonyms of sheath

• casing
• covering
• housing
• jacket
• shell
• cover
• case

Examples of sheath in a Sentence

the sheath of a sword

a piece of wire covered with a plastic sheath

Recent Examples on the Web

Make sure to put the protective sheath over the blade or wrap it to prevent injuries to anyone who inspects your luggage at the airport. —Karen Brewer Grossman, Southern Living, 12 Jan. 2026

These performances showcased many a beaded sheath dress, like the purple number seen above. —Kevin Huynh, InStyle, 10 Jan. 2026

Nuts and fatty fishes, like salmon and sardines, contain omega-3 fatty acids, which are important for building the insulating sheaths that surround the nerve fibers that carry information from one brain cell to another. —Dana G. Smith, New York Times, 6 Jan. 2026

He had been identified as a suspect after his DNA was found on a knife sheath left at the scene. —Liam Quinn, PEOPLE, 5 Jan. 2026

Word History

Etymology

Middle English shethe, going back to Old English scǣþ, scēaþ (Northumbrian sceǣþ), scēþ, going back to Germanic *skaiþjō or *skaiþō (whence also Old Frisian skēthe "sheath," Old Saxon skēdia, skēthia, Old High German skeida, Old Icelandic skeiðir, plural), probably noun derivative of *skaiđan-/skaiþan- "to separate, divide" — more at shed entry 1

Note: The original meaning of the Germanic noun was presumably "something split, separated," i.e., two pieces that are split (literally or metaphorically) and that together held the blade; note that the Old Norse noun was plural (the singular skeið meant "weaver's reed, silver spoon").

First Known Use

before the 12th century, in the meaning defined at sense 1

Phrases Containing sheath

• medullary sheath
• myelin sheath
• sheath knife

Rhymes for sheath

• neath
• teeth
• wreath
• beneath
• bequeath
• underneath

Kids Definition

sheath

noun

ˈshēth 

plural sheaths ˈshēt͟hz 

ˈshēths

1

: a case for a blade (as of a knife)

2

: a covering especially of a body part that is like a sheath in form or use

Medical Definition

sheath

noun

ˈshēth 

plural sheaths ˈshēt͟hz  ˈshēths 

1

: an investing cover or case of a plant or animal body or body part: as

a

: the tubular fold of skin into which the penis of many mammals is retracted

b

: the connective tissue of an organ or part that binds together its component elements and holds it in place

2

: condom sense 1

sheathed adjective