What does gill mean?
A gill is an organ that allows a fish or certain other aquatic animals to breathe by extracting dissolved oxygen from water. Water enters through the mouth, passes over the gill surfaces, and leaves through openings on the sides of the body. The word also has a botanical sense: the gills of a mushroom are the thin, blade-like structures beneath its cap. Less common meanings include a unit of liquid measure and, particularly in British English, a narrow ravine or rocky cleft. As a verb, to gill means to remove the gills from a fish, usually as part of preparing it for cooking. In everyday figurative expressions, gills is especially memorable: 'to the gills' means completely, while 'green about the gills' describes someone who appears sick or queasy.
The respiratory organ of a fish or other aquatic animal, or one of the plate-like structures beneath a mushroom's cap. Less commonly, the word denotes a small liquid measure or a narrow rocky cleft.
"The gill cover protected the fish's delicate gills as it moved through the shallows."
The plural gills is especially common for the paired respiratory organs of fish and for the plates beneath a mushroom cap.
To remove the gills from a fish, especially in preparation for cooking.
"She gilled the trout before stuffing it with lemon and herbs."
This verb is relatively uncommon in general use and is chiefly associated with fish preparation and specialist contexts.
The plural gills is especially natural when referring collectively to a fish's respiratory organs, the plates beneath a mushroom cap, or the paired structures on either side of the head.
"Freshwater fish generally have several pairs of gills."
Fish can breathe underwater because their gills extract dissolved oxygen from water, turning a simple-looking organ into a remarkably efficient biological filter.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does gill come from?
The word comes through Middle English from Old French gille. Its ultimate source is commonly connected with Latin gilla, although the precise origin and original sense of that Latin word are uncertain. The separate meaning for a narrow ravine developed in British English, while figurative expressions based on the appearance of a sick person's gills helped establish the word's idiomatic associations.
Related word forms
How gill is actually used
The singular gill is most natural for an individual fish organ, while gills is common when referring collectively to the organs. The related expression 'green about the gills' means looking sick or unwell, and 'to the gills' means completely or thoroughly. The verb is less common than the noun.
Easily confused with gill
A gill is an organ used by aquatic animals for breathing, whereas gilt refers to a thin layer of gold or a gilded covering.