Traditional ways of defining words depend heavily on the use of sense relations; hyponymy has played an especially important role. The classical form of a definition, going back at least to Aristotle (384–322 BC), is a kind of phrasal synonym; that is, a phrase which is mutually substitutable with the word being defined (same syntactic distribution) and equivalent or nearly equivalent in meaning.
The standard way of creating a definition is to start with the nearest superordinate term for the word being defined (traditionally called the genus proximum), and then add one or more modifiers (traditionally called the differentia specifica) which will unambiguously distinguish this word from its hyponymic sisters. So, for example, we might define ewe as ‘an adult female sheep’; sheep is the superordinate term, while adult and female are modifiers which distinguish ewes from other kinds of sheep.
This structure can be further illustrated with the following well-known definition by Samuel Johnson (1709–1784), himself a famous lexicographer. It actually consists of two parallel definitions; the superordinate term in the first is writer, and in the second drudge. The remainder of each definition provides the modifiers which distinguish lexicographers from other kinds of writers or drudges.
(22) Lexicographer: A writer of dictionaries; a harmless drudge that busies himself in tracing the [origin], and detailing the signification of words.
Some additional examples are presented in (23). In each definition the superordinate term is bolded while the distinguishing modifiers are placed in square brackets.
(23) a. fir (N): a kind of tree [with evergreen needles].8
b. rectangle (N): a [right-angled] quadrilateral.9
c. clean (Adj): free [from dirt].10
However, as a number of authors have pointed out, many words cannot easily be defined in this way. In such cases, one common alternative is to define a word by using synonyms (24a–b) or antonyms (24c–d).
(24) a. grumpy: moodily cross; surly.11
b. sad: affected with or expressive of grief or unhappiness.12
c. free: not controlled by obligation or the will of another; not bound, fastened, or attached.13
d. pure: not mixed or adulterated with any other substance or material.14
Another common type of definition is the extensional definition. This definition spells out the denotation of the word rather than its sense as in a normal definition. This type is illustrated in (25).
(25) Definitions from Merriam-Webster on-line dictionary:
a. New England: the NE United States comprising the states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, & Connecticut
b. cat: any of a family (Felidae) of carnivorous, usually solitary and nocturnal, mammals (as the domestic cat, lion, tiger, leopard, jaguar, cougar, wildcat, lynx, and cheetah)
Some newer dictionaries, notably the COBUILD dictionary, make use of full sentence definitions rather than phrasal synonyms, as illustrated in (26).
(26) confidential: Information that is confidential is meant to be kept secret or private.15
8 Hartmann & James (1998: 62).
9 Svensén (2009: 219).
10 Svensén (2009: 219).
11 http://www.merriam-webster.com/dictionary/
12 http://www.merriam-webster.com/dictionary/
13 http://www.thefreedictionary.com/free
14 http://oxforddictionaries.com/us/def...n_english/pure
15 COBUILD dictionary, 3rd edition (2001); cited in Rundell (2006).
