gill

1 gill /ˈgɪl/ noun
plural gills
1 gill
/ˈgɪl/
noun
plural gills
Britannica Dictionary definition of GILL
[count]
: the body part that a fish uses for breathing

to the gills

informal
1 
: as full as possible
2 
: very thoroughly or completely
2 gill /ˈʤɪl/ noun
plural gills
2 gill
/ˈʤɪl/
noun
plural gills
Britannica Dictionary definition of GILL
[count]
: a unit of liquid measure equal to ¹/₄ pint