burden

noun:

1. A birth.
2. The proportion of ore and flux to fuel, in the charge of a blast furnace.
3. The tops or heads of stream-work which lie over the stream of tin.
4. A fixed quantity of certain commodities.
5. Theme, core idea.
6. A phrase or theme that recurs at the end of each verse in a folk song or ballad.
7. The total amount of toxins, parasites, cancer cells, plaque or similar present in an organism.
8. A cause of worry; that which is grievous, wearisome, or oppressive.
9. A heavy load.
10. The capacity of a vessel, or the weight of cargo that she will carry.
11. A responsibility, onus.
12. The drone of a bagpipe.

verb:

1. To encumber with a literal or figurative burden.
2. To impose, as a load or burden; to lay or place as a burden (something heavy or objectionable).