From The Collaborative International Dictionary of English v.0.48 :
Bend \Bend\, n. [AS. bend. See Band, and cf. the preceding
noun.]
1. A band. [Obs.] --Spenser.
[1913 Webster]
2. [OF. bende, bande, F. bande. See Band.] (Her.) One of
the honorable ordinaries, containing a third or a fifth
part of the field. It crosses the field diagonally from
the dexter chief to the sinister base.
[1913 Webster]
Bend sinister (Her.), an honorable ordinary drawn from the
sinister chief to the dexter base.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
bend sinister
n 1: a mark of bastardy; lines from top right to bottom left
[syn: bar sinister, bend sinister]