Real Dictionary

don
countable noun: A don is a lecturer at Oxford or Cambridge University in England.
verb: If you don clothing, you put it on.

Don in American English 1
Sir; Mr.: a Spanish title of respect, used with the given name: abbrev. D
to put on (a garment, etc.); dress in (a certain color or material)
noun: a male given name, form of Donald
noun: Mr.; Sir: a Spanish title prefixed to a man's given name

Don in American English 2
a distinguished man
river in SC European Russia, flowing southward into the Sea of Azov: c. 1,200 mi (1,931 km)
noun: a goddess, the mother of Gwydion and Arianrod: corresponds to the Irish Danu
transitive verb: to put on or dress in

don in American English 3
conjunction: until

don in British English 1
noun: a Spanish title equivalent to Mr: placed before a name to indicate respect
verb: to put on (clothing)

don in British English 2
noun: a member of the teaching staff at a university or college, esp at Oxford or Cambridge
noun: a river rising in W Russia, southeast of Tula and flowing generally south, to the Sea of Azov: linked by canal to the River Volga. Length: 1870 km (1162 miles)