eigenvalue
for a linear map, the scale factor when the map is applied to a particular eigenvector
spectral radius
largest absolute value of an operator's eigenvalues
normal eigenvalue
eigenvalue of a closed linear operator such that the space admits a decomposition into a direct sum of a finite-dimensional generalized eigenspace and an invariant subspace
Dirichlet eigenvalue
fundamental modes of vibration of an idealized drum with a given shape
principal curvature
at a given point of a surface, one of the two eigenvalues of the shape operator at the point