air sac

noun

1

: one of the air-filled spaces in the body of a bird connected with the air passages of the lungs

2

: alveolus sense 1b

3

: a thin-walled dilation of a trachea occurring in many insects

Examples of air sac in a Sentence

Recent Examples on the Web

Most people have either emphysema, which happens when air sacs in the lungs called alveoli don’t function properly, or chronic bronchitis — which happens when inflammation in the airways causes mucus to accumulate in the lungs. —Lisa Rapaport, EverydayHealth.com, 27 Sep. 2024

Pneumonia is inflammation of the small air sacs deep in the lungs, called alveoli. —Kathi Valeii, Verywell Health, 4 July 2024

In addition, damaged air sacs lose their ability to stretch and shrink back. —Kathi Valeii, Verywell Health, 4 July 2024

Her primary focus was on hyaline membrane disease, sometimes called respiratory distress syndrome, in which alveoli — tiny air sacs in the lungs — do not properly inflate. —Matt Schudel, Washington Post, 3 July 2024

Word History

First Known Use

circa 1805, in the meaning defined at sense 1

Kids Definition

air sac

noun

1

: one of the air-filled spaces connected with the lungs of a bird

2

: one of the thin-walled microscopic pouches in which gases are exchanged in the lungs

Medical Definition

air sac

noun

: alveolus sense b