B

• Circular bus routes‎ (7 P)

C

• Circle of fifths‎ (3 P)
• Circles defined for a triangle‎ (14 P)
• Circles of latitude‎ (1 C, 184 P)
• Cyclical theories‎ (4 C, 9 P)

F

• Flying saucers‎ (2 C, 17 P)

M

• Metal rings‎ (5 P)

P

• Circle packing‎ (22 P)
• Piecewise-circular curves‎ (1 C, 16 P)

R

• Railway loop lines‎ (6 C, 48 P)

T

• Theorems about circles‎ (2 C, 20 P)

• Circle
• List of circle topics
• List of specially named circles

0–9

• 25 great circles of the spherical octahedron
• 31 great circles of the spherical icosahedron

A

• Annulus (mathematics)
• Apollonian circles
• Circles of Apollonius
• Area of a circle
• Aristotle's wheel paradox

B

• Benz plane
• Biarc

C

• Celestial equator
• Center-pivot irrigation
• Central angle
• Chord (geometry)
• Circle bundle
• Circle graph
• Circle of antisimilitude
• Circular arc
• Circular interpolation
• Circular knitting
• Circular layout
• Circular motion
• Circular sector
• Circular segment
• Circumference
• Circumgon
• Coin rotation paradox
• Concyclic polygon
• Crop circle
• Cyclic order
• Cyclically ordered group

D

• Diameter
• Director circle
• Disk (mathematics)
• Dividing a circle into areas
• Dotted circle

E

• Ensō
• Extouch triangle

F

• Flattening

G

• Gauss circle problem
• Generalised circle
• Geodesic circle
• Geometry of Complex Numbers
• Goat grazing problem
• Great circle
• Great-circle navigation

H

• Hart circle
• Hexafoil
• Homothetic center
• Hour circle

I

• Ice circle

J

• Johnson circles

L

• Limiting point (geometry)
• Line–circle intersection
• Lune of Hippocrates

M

• Meridian (astronomy)
• Mohr's circle
• Mrs. Miniver's problem

O

• Orthogonal circles
• Osculating circle
• Overlapping circles grid

P

• Partial cyclic order
• Pole and polar

R

• Radical axis
• Radius
• Regiomontanus' angle maximization problem
• Riemannian circle
• Robbins pentagon
• Roundel
• Roundness

S

• Smallest-circle problem
• Spherical circle
• Steiner chain

T

• Tangent circles
• Tangent lines to circles
• Three points determine a circle
• Tidal circularization
• A Treatise on the Circle and the Sphere

U

• Unit circle
• Unit disk
• Unknot

V

• Vertical circle
• Villarceau circles

W

• Woo circles