Definition of "circumference" []

• The boundary line of a circle. (noun)
• The boundary line of a figure, area, or object. (noun)
• The length of such a boundary. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "It follows directly from this discussion, that for our sphere-beings 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."
• "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 Earth-normal)."
• "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."