A husband is a married man. Your grandfather might joke that he and your grandmother have been husband and wife for so long because she has the patience of a saint and he is deaf as a post.
The word husband comes from the Old Norse hūsbōndi, where hūs meant house and bōndi meant dweller. As a verb, husband means to conserve resources and use them frugally. Because of the flooding in the area, roads are cut off and everyone is being asked to husband their supplies. This conservation of resources sense of husband also occurs in the related noun husbandry.