Oxon.

A scene from Humphry Clinker*

This may seem a bit obscure, but not if you happen to read classic British novels, especially of the epistolary sort. Like, for instance, The Expedition of Humphry Clinker by Tobias Smollett. A large percentage of the book is told through the eyes of Jery Melford, as he relates his adventures to his friend, "Sir Watkin Phillips, of Jesus College, Oxon." It's clear from context and also from listening to the audio version of the book that "Oxon." refers to Oxford, and I believe I've seen it abbreviated it this way elsewhere when it comes to addresses. But why?

My best guess is that it is actually an abbreviation for Oxford-on something. On the Thames? On the Isis? Will I even be able to find an explanation?

***

Trinity College, from Oxonia Illustrata, by David Loggans

Oxonia. It's a shortened form of Oxonia--the Latin name for Oxford. Or really, I think, Oxfordshire. As a commenter here says, it's rather old-fashioned and rarely used now, as the post office prefers you write the word "Oxfordshire" out. (Different from the U.S., as here writing the two letter abbreviation for the state has all but erased the practice of writing it out or even abbreviating it to Calif., say, as we used to do when I was a kid.)

The original Saxon word for the place was Oxenfordia, which in Norman days became Oxonford.  This was in the days when they talked like this:

Worshipfull Sirs, with all recommendacion due hadde, wille ye wete that it is so that I was at Oxonford as uppon Fryday next byfore seint Thomas day for diverse...

And so on. The source for that passage is here, in case you wanted to know what happened.  

Apparently the university and the bishopric continued to go by the name Oxonford longer than the city or the shire did, which shortened to Oxford in the 16th century,because this is where the second use of  the abbreviation oxon. comes into play. A degree from Oxford would have the abbreviation oxon tagged on the end, as, say MA (Oxon), short for 'oxoniensis'-of or related to Oxford. The equivalent degree from Cambridge would be an MA (cantab), 'cantabrigiensis' being the full word here. But we're not going to get into how Cambridge evolved from Grontabricc or whatever now. (Hint--you can blame the Normans. What else is new?)   

 
Apparently it also becomes part of an Oxford bishop's name too, but  I couldn't find an example of that, because the current Bishop of Oxford also went to Oxford and so has an oxon. after his name by default.

Now just as I'm drawing to a close, I see that the Online Etymology has a slightly different version of this story, saying that the current Oxford was Oxforde in Middle English, but goes back to the Old English Oxnaforda  of the 10th century. I mention it partly because I like the sound of that Oxnaforda.

In any case, Oxford had a cattle crossing, while Cambridge had a bridge. That's how to tell them apart.

*I found the picture from Humphry Clinker on a French wikipedia site and in this way discovered the fascinating fact that Clinker was translated into French for Gallimard by none other than Jean Giono (and Catherine d’Ivernois). Hard to believe, but here's the site.