What is "subbundle"

n. (context mathematics English) A collection of linear subspaces of the fibers ''V_x'' of ''V'' at ''x'' in ''X'' (where ''V'' is a vector bundle and ''X'' a topological space), that make up a vector bundle in their own right.

In mathematics, a subbundle U of a vector bundle V on a topological space X is a collection of linear subspaces U of the fibers V of V at x in X, that make up a vector bundle in their own right.

In connection with foliation theory, a subbundle of the tangent bundle of a smooth manifold may be called a distribution (of tangent vectors).

If a set of vector fields Y span the vector space U, and all Lie commutators [Y,Y] are linear combinations of the Y, then one says that U is an involutive distribution.