Not moral, without morals. Contrary to good morals; inconsistent with the rules and principles of morality which regard men as living in a community, and which are necessary for the public welfare, order, and decency. Immoral consideration. One contrary to good morals, and therefore invalid. Contracts based upon an immoral consideration are generally void. Immoral contracts. Contracts founded upon considerations contra bonos mores are void.
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.