A spectrum is a distribution of a signal arranged according to characteristics like frequency.
The nuclear spin is a property of a nucleus defining the nuclear magnetic momentum.
The term relaxation describes several processes by which nuclear magnetization prepared in a non-equilibrium state return to the equilibrium distribution.
Fourier transform is an algorithm that converts a signal which is intensity vs time into a spectrum which is amplitude vs frequency.
A metabolite is a substance that takes part in the process of metabolism.