
Circumference
In geometry, the circumference (from Latin circumferentia, meaning “carrying around”) of a circle is the (linear) distance around it. That is, the circumference would be the length of the circle if it were opened up and straightened out to a line segment. Since a circle is the edge (boundary) of a disk, circumference is a special case of perimeter. The perimeter is the length around any closed figure and is the term used for most figures excepting the circle and some circularlike figures such as ellipses.
Informally, “circumference” may also refer to the edge itself rather than to the length of the edge.

Circumference (noun)
The line that bounds a circle or other twodimensional figure

Circumference (noun)
The length of such a line

Circumference (noun)
The surface of a round or spherical object

Circumference (noun)
The length of the longest cycle of a graph

Circumference (verb)
To include in a circular space; to bound.

Girth (noun)
A band passed under the belly of an animal, which holds a saddle in place.

Girth (noun)
The part of an animal around which the girth fits.

Girth (noun)
One’s waistline circumference, most often a large one.

Girth (noun)
A small horizontal brace or girder.

Girth (noun)
The distance measured around an object.

Girth (noun)
The length of the shortest cycle in a graph.

Girth (verb)
To bind as if with a girth or band.

Circumference (noun)
the enclosing boundary of a curved geometric figure, especially a circle.

Circumference (noun)
the distance around something
“babies who have small head circumferences”
“a rope two inches in circumference”

Girth (noun)
the measurement around the middle of something, especially a person’s waist
“an ivyclad tree of immense girth”
“a pike with a girth of 24 inches”
“idle men of great girth”

Girth (noun)
a person’s waist or stomach, especially when large
“he tied the knotted towels around his girth”

Girth (noun)
a band attached to a saddle and fastened around a horse’s belly to keep the saddle in place.

Girth (verb)
surround; encircle
“the four seas that girth Britain”