- continuum
- converge
- convergent
- converging
- convex
- contravariant
- corollary
- corresponding
- cotangent
- cosesant
- cosine
- cubic
- cuboid
- curvature
- critical
- cusp
- cuspidal
- cube
- cubical
- cycloid
- cylinder
- decimal
- decrement
- defect
- decagonal
- decahedral
- degree
- decagon
- decahedron
- deficiency
- deflexion
- deflection
- derivation
- develop
- denominator
- dependant
- dependent
- diametrical
- difference
- differential
- descriptive
- developable
- development
- deviation
- diametral
- dihedon
- dimension
- dimensional
- dimensionless
- depression
- diameter
- differentiate
- differentiation
- director
- discrete
- dissimilitude
- directrices
- directrix
- discontinuity
- discriminant
- dissimilar
- dissimilarity
- division
- divi
- dividend
- divisible
- doddecagon
- dodecagon
- dodecahedron
- doddecahedron
- dual
- dualistic
- duality
- element
- eliminable
- eliminate
- elimination
- ellipse
- ellipsoid
- elliptic
- elliptical
- enneagon
- enunciation
- envelope
- epicycle
- epicycloid
- epicycloidal
- equate
- equation
- equational
- equiangular
- equidistant
- equilateral
- equimultiple
- epicyclic
- erect
- erection
- escribed
- euclid
- euclidean