constructible number
real number that can be geometrically constructed with compass and straightedge from a unit segment in a finite number of steps
quadratic irrational
irrational root of a quadratic equation with integer coefficients
rational number
quotient of two integers
metallic ratio
generalization of the golden ratio; positive real number x such that x = n + 1/x, for a natural number n
golden ratio
ratio between two quantities whose sum is at the same ratio to the larger one