echt adj., echt- prefix - real, true, pure, genuine, authentic, natural, etc.; the opposite of ersatz.
eigen- prefix from eigen, eigen- "own": proper, characteristic; used in technical terms in physics and mathematics, for example in eigenfrequency, eigenvector, eigenvalue, eigenfunction, eigenspace, eigenstate. Contrast with
ersatz n., adj. from Ersatz- "substitute": imitation or substitute (inferior); artificial; opposite of echt.
Also, ansatz n. from Ansatz "statement, formulation; beginning, start": a technical term used by mathematicians and especially by theoretical physicists to describe a solution to a problem which is guessed (usually with some free parameters).
Finally, Müesli.