If you've heard of the word unprepossessing, it probably comes as no surprise to you that there's also a prepossessing. You may not know, however, that both derive from the verb prepossess, which is also still used in English, although it's quite rare. When prepossess first appeared in print in English in the early 17th century it meant "to take previous possession of," but that sense is now obsolete. The adjective prepossessing came into use later in that century and is based on a later sense, "to influence favorably beforehand." Someone or something that is prepossessing, therefore, makes a good first impression.