Who is a refugee?

Who is a refugee?  It might seem straight forward but it isn't.
If I lost my house in a financial crisis and moved abroad with nothing but a couple of suitcases, am I a refugee? I suppose you need to be persecuted because of your sexuality, politics or ethnicity but what does it mean to be persecuted?

Were Jews who left the USSR in the 'Seventies (and allowed to take only two suitcases) persecuted? If they were persecuted for being Zionists, couldn't they have chosen not to be Zionists?
Are refugees people who are forced to leave their countries? But if they are persecuted for being Zionists and then leave willingly to a country that adopts them, then are they still refugees?  Were they refugees when they arrived?
What about the Palestinians, who having arrived as refugees, were persecuted by their host countries in order to force them to maintain their refugee status. Are they now refugees because of 1948 or because of their treatment by their Arab hosts?

Perhaps a refugee is someone who has formal UN documentation (and recognition).  For example, Palestinian refugees carry UN documentation and are "recognized refugees". My father was also a recognized refugee.  He arrived in England in 1939 with no citizenship and was at some point given UN refugee status which he kept until 1968, when he applied for British citizenship.  By that time he had a house in Muswell Hill and a family, he hadn't been a refugee for years. So does the documentation count?

In contrast only very few of the Jews who migrated to Israel between 1948 and 1958, had refugee status and yet most of them were fleeing persecution in the Arab world and Eastern Europe. Were they refugees?

At the time, Israel didn't regard them as refugees because it gave them citizenship and undertook to house and feed them.  To the Israelis they were coming home, but now 60 years later we look back and say they were refugees, this is especially true of the Jews who left the Arab world, many of whom left at very short notice  (perhaps the length of time you have to plan your exit defines your refugee status).  So many arrived that many lived in camps for years because Israel couldn't house them (does living in a camp make you a refugee?).

The issue is now raised because of the many Palestinians claiming refugee status. Unlike the Jews, the Palestinians have UN documentation and lack formal state citizenship, but many have lived in the same houses in the same countries for generations and their connection to "Palestine" is by now very tenuous.
The Jews are clearly no longer refugees, but Israel invested a great deal in caring for them at the time, and they left very valuable property behind so perhaps that is sufficient.