Moreover, meaning 6 is on its way to being archaic-- most dictionaries mark archaic definitions, something seems to be wrong with yours. :
You used moral as an adjective in you post. Since pre marital sex is widely considered wrong conduct, which one were you referring to?
1. of, pertaining to, or concerned with the principles or rules of right conduct or the distinction between right and wrong; ethical: moral attitudes.
2. expressing or conveying truths or counsel as to right conduct, as a speaker or a literary work; moralizing: a moral novel.
3. founded on the fundamental principles of right conduct rather than on legalities, enactment, or custom: moral obligations.
4. capable of conforming to the rules of right conduct: a moral being.
5. conforming to the rules of right conduct (opposed to immoral): a moral man.
6. virtuous in sexual matters; chaste.
7. of, pertaining to, or acting on the mind, feelings, will, or character: moral support.
8. resting upon convincing grounds of probability; virtual: a moral certainty.