Burden
WordNet
noun
(1) Weight to be borne or conveyed
(2) An onerous or difficult concern
"The burden of responsibility"
"That's a load off my mind"
(3) The central idea that is expanded in a document or discourse
(4) The central meaning or theme of a speech or literary work
verb
(5) Impose a task upon, assign a responsibility to
"He charged her with cleaning up all the files over the weekend"
(6) Weight down with a load