Even though it's been discussed in blogs before, and I'm going to quote the text of another, I can't let Simchat Torah go by without mentioning Avraham Yaari's explanation of the origin of the term chatan torah חתן תורה (or hatan torah). From Bloghead:
In the runup to Simchat Torah I've been skimming through bits of Avraham Ya'ari's classic history of the festival, 'Toldot Chag Simchat Torah' ('The Origins of the Festival of Simchat Torah,' pub. in Hebrew by Mossad Harav Kook). Whilst we often pride ourselves on / lament (depending on who you are...) the unchanging nature of our tradition, this history shows how enormously fluid some of our traditions actually are. Among the fascinating points:
Simchat Torah originated in Babylon and was not celebrated in Israel until the end of the Gaonic period (ie. - totally Diaspora festival!). The reason is that in Babylon, the Jews had the same one-year cycle for reading the Torah we do today, whereas in Israel they finished the Torah every three / three and a half years, and not always on the same date. When the EY communities finished the Torah, they would hold a festive meal, but no 'Simchat Torah' as we know it. The festival originally did not involve reading from Bereshit, but merely finishing Devarim. Hence, the original term was not 'chatan Torah' but 'chatam Torah' -- sealer of the Torah. There was, of course, no chatan Bereshit.
I read about חתן תורה / חתם תורה in Sperber's Minhagei Yisrael, where he quotes Yaari, and provides additional sources.
While I've talked about chatan before, I don't know if the expansion of chatan to "prizewinner, laureate" - as in chatan pras yisrael חתן פרס ישראל , Israel Prize Laureate - developed from the terms chatan torah and chatan bereshit.