We do not currently know of any antonyms for morganatic.
The adjective morganatic is defined as:
Designating a marriage (or the wife involved) between a man of higher rank and a woman of lower rank, often having various legal repercussions (typically that such a wife has no claim on the husband's possessions or title). It was not an aspect of English law, but was common in other royal houses, especially in Germany.
