from The Century Dictionary and Cyclopedia
- In botany, having the flanks of the organ flattened surfaces: applied to a particular kind of bilaterally symmetrical organs, as the leaves of some species of Iris, in contradistinction from bifacial or dorsiventral organs, or those with an evident upper and under surface, as in most leaves.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. having identical parts on each side of an axis
Sorry, no etymologies found.
What you and the bank have got is a isobilateral contract when you exchange "promises to pay".