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Synonyms

sac

1 American  
[sak] / sæk /

noun

  1. a baglike structure in an animal, plant, or fungus, as one containing fluid.


Sac 2 American  
[sak, sawk] / sæk, sɔk /

noun

plural

Sacs,

plural

Sac
  1. Sauk.


SAC 3 American  
[sak] / sæk /
Or S.A.C.

noun

  1. Strategic Air Command.


SAC 1 British  

abbreviation

  1. Special Area of Conservation

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

sac 2 British  
/ sæk /

noun

  1. a pouch, bag, or pouchlike part in an animal or plant

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

sac Scientific  
/ săk /
  1. A pouch or pouch-shaped structure in an animal or plant, often containing liquids. The human bladder is a sac.


Other Word Forms

  • saclike adjective

Etymology

Origin of sac

First recorded in 1735–45; from Latin saccus “bag, sackcloth”; sack 1

Explanation

A sac is a hollow space or container. While any pocket or pouch can be called a sac, the word usually refers to a small enclosed space that occurs in nature, like a spider's egg sac or a squid's ink sac. You might put your groceries in a sack, but without the “k” a sac is smaller and attached to a plant or animal. Human fetuses grow inside an amniotic sac, and seed plants produce pollen inside sacs as well. Since the mid-1700s, sac has been used to mean "biological pocket," from the Latin root word saccus, or "bag." If you’re not sure which sac to use, it’s almost always the other one unless you’re in biology class.

Keep Reading on Vocabulary.com

Vocabulary lists containing sac

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Meanwhile, the cul de sac, a street design much in favor with the architects of suburban developments, have become artificial catchments for these highly flammable weeds.

From The Wall Street Journal • Nov. 17, 2025

The next day she was diagnosed with pericarditis - an inflammation of the fluid-filled sac around the heart.

From BBC • Oct. 12, 2025

“It’s quality at-bats, quality outs, moving guys over, getting sac flies, bringing defenses in if you move them over,” Freeman said.

From Los Angeles Times • Sep. 14, 2025

A sac fly from Kendle in the fourth and a run-scoring groundout by Woody Hadeen pushed the Irvine advantage to 6-2.

From Seattle Times • Jun. 2, 2024

But Templeton worked away at the job, and managed to cut the sac adrift and carry it to the ground, where he dropped it in front of Wilbur.

From "Charlotte's Web" by E.B. White