1. the duty of proving a disputed charge
The Collaborative International Dictionary of English v.0.48:
Burden \Bur"den\ (b[^u]"d'n), n. [Written also burthen.] [OE.
burden, burthen, birthen, birden, AS. byr[eth]en; akin to
Icel. byr[eth]i, Dan. byrde, Sw. b["o]rda, G. b["u]rde, OHG.
burdi, Goth. ba['u]r[thorn]ei, fr. the root of E. bear, AS.
beran, Goth. bairan. [root]92. See 1st Bear.]
1. That which is borne or carried; a load.
Plants with goodly burden bowing. --Shak.
2. That which is borne with labor or difficulty; that which
is grievous, wearisome, or oppressive.
Deaf, giddy, helpless, left alone,
To all my friends a burden grown. --Swift.
3. The capacity of a vessel, or the weight of cargo that she
will carry; as, a ship of a hundred tons burden.
4. (Mining) The tops or heads of stream-work which lie over
the stream of tin.
5. (Metal.) The proportion of ore and flux to fuel, in the
charge of a blast furnace. --Raymond.
6. A fixed quantity of certain commodities; as, a burden of
gad steel, 120 pounds.
7. A birth. [Obs. & R.] --Shak.
Beast of burden, an animal employed in carrying burdens.
Burden of proof [L. onus probandi] (Law), the duty of
proving a particular position in a court of law, a failure
in the performance of which duty calls for judgment
against the party on whom the duty is imposed.
Syn: Burden, Load.
Usage: A burden is, in the literal sense, a weight to be
borne; a load is something laid upon us to be carried.
Hence, when used figuratively, there is usually a
difference between the two words. Our burdens may be
of such a nature that we feel bound to bear them
cheerfully or without complaint. They may arise from
the nature of our situation; they may be allotments of
Providence; they may be the consequences of our
errors. What is upon us, as a load, we commonly carry
with greater reluctance or sense of oppression. Men
often find the charge of their own families to be a
burden; but if to this be added a load of care for
others, the pressure is usually serve and irksome.
WordNet (r) 3.0 (2006):
burden of proof
n 1: the duty of proving a disputed charge