Burden

1. n. A birth.
2. n. That which is borne or carried; a load.
3. n. That which is borne with labor or difficulty; that which is grievous, wearisome, or oppressive.
4. n. The capacity of a vessel, or the weight of cargo that she will carry; as, a ship of a hundred tons burden.
5. n. The tops or heads of stream-work which lie over the stream of tin.
6. n. The proportion of ore and flux to fuel, in the charge of a blast furnace.
7. n. A fixed quantity of certain commodities; as, a burden of gad steel, 120 pounds.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.