[Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/dictionaries/school/w/sac.html)

[home](https://md.mova.elamur.ai/free/en/) / [dictionaries](https://md.mova.elamur.ai/free/en/dictionaries/) / [The school dictionary](https://md.mova.elamur.ai/free/en/dictionaries/school/) / sac

[← S](https://md.mova.elamur.ai/free/en/dictionaries/school/S/)

# sac

«sac» in Mova's school dictionary: **a small bag-like part inside a plant or animal, often…** — its meaning for a pupil, its sense in the lessons and examples, with 2 sentences of Mova's corpora that use it.

### part of speech

noun (a sac, sacs)

### meaning for a pupil

1) A sac is a small bag-like part inside a plant or animal, often filled with liquid or air, like an egg sac or an ink sac. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#m1)

2) (science) In a spider, an egg sac is a silk bag holding its eggs; in a squid or octopus, the ink sac squirts dark ink to escape enemies. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#m2)

### sense in the lessons

In science lessons «sac» comes up in life cycles (spider egg sacs, frogspawn), animal defences (the octopus ink sac), the human body (air sacs in the lungs, called alveoli) and plant seeds. It is a science word; in everyday talk people say «bag» or «pouch».

### examples

- The spider guarded its egg sac. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x1)
- The octopus squirted ink from its ink sac. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x2)
- Our lungs have millions of tiny air sacs. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x3)
- Frogs puff up a vocal sac to croak. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x4)
- The baby spiders hatched from the egg sac. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x5)
- A bee's sting has a venom sac. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/#x6)

### note

Plural «sacs». Homophone trap: «sac» (a bag in a body) and «sack» (a large bag; or to fire someone from a job). Science writing uses «sac».

### In the corpora

- [Octopuses change colour in a flash with millions of tiny colour sacs in their skin, to hide, show mood or startle enemies.](https://md.mova.elamur.ai/free/en/corpora/school/biology/234-animal-minds-the-octopus-escape-artist-and-puzzle-solver/9/)
- [Oxygen passes into the blood through the thin walls of the air sacs, and carbon dioxide passes out to be breathed away.](https://md.mova.elamur.ai/free/en/corpora/school/biology/262-human-body-deeper-lungs-stomach-and-guts/8/)

### Trees and pragmatics

[Every meaning and example of «sac» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/S/sac/), each sentence with its dependency tree and frames.