A morganatic marriage is like playing pretend tea-party, where sometimes your guests are not invited to live with you in your house forever.
If you are a prince, for example, and you want to marry a lady, but she is not from the royal family, then she would not have the same title or privileges as you, even if you are married. This kind of marriage in which the wife (or husband) is not of the same rank or status as the other person is called a morganatic marriage.
So, in a way, if you are playing tea-party with your friends, they might pretend to be your visitors for a little while, but when the game is over, they go back to their own houses. Similarly, in a morganatic marriage, the partner with the lower status may not be able to live in the same house as the other person or receive the same benefits, rankings, or privileges as the other person.
This type of marriage is often seen in royal families, where a prince or king marries someone of lower status, but still wants to give them some protection, financial security and a social status. It is also said that this word originated from the Latin term 'matrimonium ad morganaticam', which means 'marriage on the morning-gift'.
So, in conclusion, a morganatic marriage is when someone who is of lower status marries someone who is of higher status, but they do not get all the same benefits and privileges that the higher status person has, and it is like playing a pretend game where your guests are not allowed to stay with you forever.