To don means to put on, as in clothing or hats. A hunter will don his camouflage clothes when he goes hunting.
What is the opposite of don, an old-fashioned word meaning "to put on?" Doff another old-fashioned word meaning "to take off." These two words have something else in common - both are contractions from the 14th century English expressions do on and do off respectively. Don your boots before going out in the snow and doff them when you come inside again! A don is also a Spanish nobleman and a dean of a college at Oxford or Cambridge, but these meanings come from the Latin dominus meaning "master."