Origin of eigenvaluepartial translated, translation of German eigenwert ; from eigen, own, particular + wert, value
Origin of eigenvaluePartial translation of German Eigenwert : eigen-, peculiar, characteristic (from eigen, own, from Middle High German, from Old High German eigan; see aik- in Indo-European roots) + Wert, value.
When unqualified, as in the above example, eigenvalue conventionally refers to a right eigenvalue, characterised by for some right eigenvector . Left eigenvalues, charactarised by also exist with associated left eigenvectors . For commutative operators, the left eigenvalues and right eigenvalues will be the same, and are referred to as eigenvalues with no qualifier.
eigen- + value