"A gifted small girl has explained that pins are a great means of saving life, 'by not swallowing them.' " ~Charles Edward Montague, Dramatic Values
Dictionary.com is a wonderful place that I often visit multiple times in a day but, as everything, it has flaws. If you managed to ask the earth's nearly 7 billion people to define the word 'door', how many do you think would say,
"a movable, usually solid, barrier for opening and closing an entranceway, cupboard, cabinet, or the like, commonly turning on hinges or sliding in grooves"?
Personally, I don't think that many would. Some might give the same message but with less specific wording.