This list of circle topics includes things related to the geometric shape, either abstractly, as in idealizations studied by geometers, or concretely in physical space. It does not include metaphors like "inner circle" or "circular reasoning" in which the word does not refer literally to the geometric shape.

Geometry and other areas of mathematics

Physical sciences and engineering

• Centrifugal force
• Centripetal force
• Circle of confusion
• Circle of forces
• Circular dichroism
• Circular orbit
• Mohr's circle
• Non-uniform circular motion
• Thomson problem
• Uniform circular motion

Geography

• Circle of latitude
  • List of circles of latitude
  • Polar circle
    • Arctic Circle
    • Antarctic Circle
  • Equator
  • Tropic of Cancer
  • Tropic of Capricorn
• Great-circle distance
• Position circle

Artifacts

• Addendum circle
• Belt problem
• Center pivot irrigation
• Circular ditches
• Circular slide rule
• Compass (drafting)
• Crop circle
• Dip circle
• List of gear nomenclature
• Peaucellier–Lipkin linkage
• Pitch circle
• Repeating circle
• Timber circle
• Traffic circle
  • List of circles in Washington, D.C.
  • List of traffic circles in New Jersey
• Setting circles
• Stone circle
• Wheel

Glyphs and symbols

• Borromean rings
• Circled dot (disambiguation)
• Circles in Polish mythology
• Crescent
• Dotted circle
• Enso
• Magic circle
• Olympic emblem
• Ouroboros
• Petosiris to Nechepso
• Quatrefoil
• Ring (diacritic)
• Roundel
• Sacred Chao
• Shield of the Trinity
• Solar symbols
• Squared-circle postmark
• Sun cross
• Symbol of Tanit
• Trefoil
• Triquetra
• Vesica piscis
• Triple Goddess symbol
• Yin and yang