hypotenuse, hexagon, half, hectometre, hectogram (etc), Hamiltonian, hyperbola, hyperbolic, hypergeometric are some.
kilometers
y-axis
Frequency.
Hypotenuse, hexagon
universal graph, uranium, umbra
The Greek letter Kappa (κ) is sometimes used in math. For example, in differential geometry, the curvature of a curve is given by κ.
vector
hypotenuse
Geometry
linear
Quadratic, quotient.
integers?