underburden

Verb

 * 1) To give too light a burden; to assign less than a fair share.
 * 2) To assign less work than someone or something is capable of.
 * 1) To assign less work than someone or something is capable of.
 * 1) To assign less work than someone or something is capable of.
 * 1) To assign less work than someone or something is capable of.

Noun

 * 1)  The rock and subsoil that lies below a mineral deposit such as a coal seam.