What is the meaning of burden?

noun

• An onerous or difficult concern.
  • usage: "the burden of responsibility"; "that's a load off my mind"
  • synonyms: load, encumbrance, incumbrance, onus
• Weight to be borne or conveyed.
  • synonyms: load, loading
• The central meaning or theme of a speech or literary work.
  • synonyms: effect, essence, core, gist
• The central idea that is expanded in a document or discourse.

verb

• Weight down with a load.
  • synonyms: burthen, weight, weight down
• Impose a task upon, assign a responsibility to.
  • usage: "He charged her with cleaning up all the files over the weekend"
  • synonyms: charge, saddle