WordGarden.iogill
C2Pronunciation
UK
- /dʒˈɪl/
US
- /ˈɡɪl/
Meanings
Noun
a respiratory organ of a fish or other aquatic animal
one of the thin plates under a mushroom cap
an old liquid measure equal to a quarter of a pint
More meaningsFewer meanings
a narrow ravine or small stream, especially in northern English place names
Beyond the definition
You probably picture a fish when you hear the word "gill." These are the organs that let fish, and some other water animals, take oxygen from water. We often notice them as slits on the side of the head, but the real structures inside are soft and fine.
But "gill" is not just about fish. It can also mean the thin parts under a mushroom cap, and sometimes it is used for narrow vent-like openings in a machine or design. So the word usually points to something that helps with breathing, airflow, or spreading.
The primary meaning of "gill" refers to the respiratory organ found in aquatic animals like fish, crustaceans, and some amphibians. These organs extract dissolved oxygen from water and release carbon dioxide, essentially allowing the animal to "breathe" submerged. Within the gills, tiny, feathery filaments maximize the surface area for efficient gas exchange. In sharks, the gill openings appear as vertical slits, while a goldfish has a bony protective flap, called an operculum, covering its gills.
However, "gill" is not limited to animal anatomy. In mycology, it refers to the thin radiating ridges found under the cap of certain mushrooms; these structures produce and release spores. You might also encounter "gill" in technical contexts describing narrow ventilation openings. For example, some engines or building designs feature gill-like vents to improve airflow.
Historically, "gill" was also used as a unit of liquid volume, typically equal to a quarter of a pint (about 118 mL in the US or 142 mL in the UK), though this meaning is now uncommon except in older or traditional measurements. Whether you are talking about fish, mushrooms, vents, or old measures, the word usually refers to a part, opening, or amount with a clear practical use.
Examples
- 1
Fish anatomy
The fish opened and closed its gills as it lay in the net.
- 2
Injury
If a fish's gills are damaged, it may not survive for long.
- 3
Crowded place
By lunchtime, the little cafe was packed to the gills.
- Phrasepacked to the gills
extremely full or crowded
See also
Forms and spellings
2 forms open this card.
Main spelling
- gillnoun
Forms
- gillspluralnoun