Word Meaningcontrastive sound unit.
Many dictionary definitions are expressed in terms of the function that
something serves. For example, WNWD defines hinge as “a joint or device
on which a door, gate, lid, etc. swings” (p. 664). Suppose that no one had
oiled the hinge in decades and it could no longer swing—is it still a hinge?
The answer is undoubtedly “yes,” just as a dog with no tail is still a dog.
These may be defective members of their categories, but they are still mem-
bers. How much change must be endured before something is no longer
accepted as a member of its original category? What does a dog have to give
up before it is no longer a dog? Whatever the answer to that question is, it is
clear that we can adjust our assumptions about what it takes to be a member
of a category to accommodate defective members.
As we have seen, categories typically have many members, in fact, po-
tentially indefinitely many. The more general categories have multiple sub-
categories, which in turn may have their own subcategories. However, some
category members are viewed as better members of the category than others.
For instance, chairs and sofas are regarded as better items of furniture than
refrigerators; robins and sparrows are better birds than penguins or ostrich-
es; shirts and skirts are better pieces of clothing than shoes and socks. This
layering of category members extends even to things defined in terms of
necessary and sufficient conditions, such as prime numbers: for example, 3
is a better prime number than 23, even though both fit the technical defini-
tion. It has been argued that categories are structured around a central, most
typical member, or prototype, e.g., chairs in the case of furniture, robins in
the case of birds, and so on.
Exercise
Let’s try to determine the prototypical member of a category. As quick-
ly as you can, write out a list of ten vegetables. Then compile the lists
of all the students in your class. Order the vegetable names accord-
ing to their frequency in the lists. Then take the three most frequent
words and check how early they occur in the lists. Generally, the most
frequent ones will occur early. The earliest and most frequent word
probably represents the most prototypical member of the category of
vegetables.
Dictionaries indicate certain aspects of prototypicality in their defini-
tions. For example, WNWD (p. 1051) describes a penguin as a “flightless