1. The boundary line of a circle.
a. The boundary line of an area or object.
b. Abbr. c or circ. The length of such a line.
3. The margin or area surrounding something.
[Middle English, from Old French circonference, from Latin circumferentia, from circumferēns, circumferent-, present participle of circumferre, to carry around : circum-, circum- + ferre, to carry; see bher-1 in the Appendix of Indo-European roots.]
cir·cum′fer·ential (-fə-rĕnshəl) adj.
Synonyms: circumference, circuit, compass, perimeter, periphery
These nouns refer to a boundary or area around the outer edge of something: drove around the circumference of the city; followed the circuit around the park; stayed within the compass of the schoolyard; walked the perimeter of the estate; fenced the periphery of the property.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.