A short written form of 'university', used in the names of American universities: Indiana U., Ohio State U., Boston U. You see it in newspaper headlines, in sports writing, on college merchandise, and in casual writing where space is tight — it is not formal, and a university would not use it on an official document. Note where it sits: it comes after the place name in this American style (Indiana U.), while the full name is 'Indiana University'. In British writing this abbreviation is rare. There is a separate, related use in American speech: students call their own campus 'the U' (no full stop), meaning 'our university' — 'She's studying at the U.' Careful, though: this letter stands for many other things in other contexts (uranium, the German U-Bahn, and in old British talk 'U' meant upper-class speech), so let the sentence tell you which one you have.