(algebra) variable / (computing) variable

(algebra) constant

(mathematics, chemistry) an equation

May

(calculus) constant of integration - a constant term added to a particular antiderivative to make it represent its whole family of antiderivatives

X-ray (short wavelength electromagnetic radiation) / X-ray (photograph made with X-rays)

x-axis (axis drawn from left to right)

Alternative spelling of クリスマス (“Christmas”)

(physics, chemistry) Avogadro's number, Avogadro constant (number of atoms present in 0.012 kilograms of isotopically pure Carbon-12)

(physics) the Planck's constant