What is Immoral?

Legal Definition
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.
See also
-- Black's Law Dictionary
Legal Definition
Contrary to public welfare; against public morals. See 112 Ga. 426, 52 L. R. A. 271, 37 S. E. 729.
-- Ballentine's Law Dictionary