Convex
A Set in Euclidean Space 
is convex if it contains all the Line Segmentsconnecting any pair of its points. If the Set does not contain all the Line Segments, it iscalled Concave.
References
Croft, H. T.; Falconer, K. J.; and Guy, R. K. ``Convexity.'' Ch. A in Unsolved Problems in Geometry. New York: Springer-Verlag, pp. 6-47, 1994.
- Majorant
- Major Axis
- Major Triangle Center
- Makeham Curve
- Malfatti Circles
- Malfatti Points
- Malfatti's Right Triangle Problem
- Malfatti's Tangent Triangle Problem
- Malliavin Calculus
- Mallow's Sequence
- Malmstén's Differential Equation
- Maltese Cross
- Maltese Cross Curve
- Malthusian Parameter
- Mandelbar Set
- Mandelbrot Set
- Mandelbrot Tree
- Mangoldt Function
- Manifold
- Mantissa
- Map
- Map Coloring
- Mapes' Method
- Map Folding
- Mapping (Function)