Definitions
from The American Heritage® Dictionary of the English Language, 4th Edition
 n. The boundary line of a circle.
 n. The boundary line of a figure, area, or object.
 n. The length of such a boundary.
from Wiktionary, Creative Commons Attribution/ShareAlike License
 n. The line that bounds a circle or other twodimensional figure
 n. The length of such a line
 n. The surface of a round or spherical object
 v. To include in a circular space; to bound.
from the GNU version of the Collaborative International Dictionary of English
 n. The line that goes round or encompasses a circular figure; a periphery.
 n. A circle; anything circular.
 n. The external surface of a sphere, or of any orbicular body.
 transitive v. To include in a circular space; to bound.
from The Century Dictionary and Cyclopedia
 To include in a circular or spherical space.
 n. The line that bounds a circle; by extension, the bounding line of any regular plane curvilinear figure; a periphery: as, the circumference of a circle or an ellipse. The circumference of a sphere is that of a great circle of the sphere.
 n. Hence Loosely, any bounding line: as, the circumference of a city.
 n. The space included in a circle; anything circular in form.
 n. A going about; circumlocution.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
 n. the boundary line encompassing an area or object
 n. the length of the closed curve of a circle
 n. the size of something as given by the distance around it
Etymologies
Examples

It follows directly from this discussion, that for our spherebeings the circumference of a circle first increases with the radius until the circumference of the universe is reached, and that it thenceforward gradually decreases to zero for still further increasing values of the radius.
Chapter 31. The Possibility of a “Finite” and Yet “Unbounded” Universe

This means the circumference is about 1000 meters, so v is 1000 meters per minute, which yields a simulated gravity about 1/6 of Earth's  the same as the moon (though the people inside move as though the gravity is Earthnormal).

Paul Rodriguez was a Mexican porter who from the upper and lateral part of his head had a horn 14 cm in circumference and divided into three shafts, which he concealed under a cap.

It makes tubes 44 stitches in circumference or straight pieces up to 44 stitches wide and takes up to a sort of medium chunky weight of yarn  just right for a tubular scarf but a bit narrow to make hats.

Lord Howe is a ring of land some one hundred and fifty miles in circumference, several hundred yards wide at its widest, and towering in places to a height of ten feet above sea level.

The atoll of Hikueru lay low on the water, a circle of pounded coral sand a hundred yards wide, twenty miles in circumference, and from three to five feet above highwater mark.

Unfortunately that means my jeans are quite uncomforable to wear, because the belt circumference is now at least two holes smaller than the waistband of the jeans.

The park circumference is approximately 40 kilometers (km), extending from the bridge at Ürgüp then leading north for 6 km following the River Damsa.
Göreme National Park and the Rock Sites of Cappodocia, Turkey

Large Hadron collider is 27 Km in circumference and will accelerates protons to 99. 99999% the speed of light (I might not have gotten the right number of 9s, sorry if this spoils your calculations if you are trying this at home).

The method of calculating mass from femur circumference is clearly not very reliable, but I like it anyway, because (as detailed in the supp.inf. of the Turiasaurus paper) for giant sauropods it gives estimates as low as when conventional methods are combined with very low assumed densities (to account for all the air sacs)  29 t for Brachiosaurus brancai.
fbharjo commented on the word circumference
mercuric fence
January 27, 2016