The same as an eigen value or characteristic value of a matrix (see Characteristic polynomial).
The value of a characteristic class of the tangent bundle (or another interesting bundle) of a (closed) manifold on a fundamental cycle of this manifold.
|[a1]||J.W. Milnor, J.D. Stasheff, "Characteristic classes", Princeton Univ. Press (1974) MR0440554 Zbl 0298.57008|
Characteristic number. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Characteristic_number&oldid=53837