There are two sub-classes of monolingual dictionaries that are particularly relevant for us: those for foreign students and the "special" or "specific" ones.

A common monolingual dictionary, with a traditional organisation, is usually intended for the use of native speakers of the language, who may be interested in the exact spelling and or pronunciation of a word and in the rigorous, precise and detailed definition of its meaning(s). This can lead to paradoxical results. If you look up an easy word like horse in the Shorter OED this is what you find:

We have selected only a part of the first meaning as a noun, omitting pronunciation, etymology, plural forms, other meanings, phraseology, and the second entry, the verb to horse (in all, these entries in the SOED consist of a total of over 1900 words or 2½ pages). Our selection is enough to see that highly technical words like perissodactyl, ungulate and Equidae are used, as well as such words as solid-hoofed, mammal and draught that are not so technical but are certainly less frequent than horse, the word they define. But of course if an Englishman ever looks up a word like horse — a word he certainly knows very well — these complex terms may well be exactly the information he is looking for.

With the diffusion of the teaching of English as a foreign language, the need has emerged for dictionaries for foreigners, explaining words and phrases in the simplest possible way, perhaps using pictures and/or graphs to make comprehension easier.

The first of these was the Oxford Advanced Learner's Dictionary of Current English (OALDCE), edited by A.S. HORNBY. As this was a pioneering work, some of its developments are worth examining in greater detail, also because this analysis will be of help in the description and discussion of other dictionaries.

The OALDCE was written in the years 1937-40 and first printed in 1948, exactly when the former British Empire gave way to the British Commonwealth of Nations. The next editions were:

1. in 1963, edited in collaboration with E.V. GATENBY and H. WAKEFIELD (from this, a bilingual edition edited by M. SKEY and published by SEI was drawn);
2. in 1974, with a cheaper and more compact version in 1980;
3. in 1989 (edited by A. P. Cowie) and
4. in 1995 (edited by Jonathan Crowther).

One of the new important features was the introduction of grammatical information; this may seem obvious now, after over a half century of dictionaries for foreign learners, but it was a true innovation at the time. Native speakers of the language do not need to be told, for example, that the form *informations does not exist; they know from experience — they have never heard or seen that form in their lives. Monolingual dictionaries for natives usually limit themselves to signalling the class (noun, verb, etc.) to which the word belongs.

The OALDCE was the first dictionary to signal uncountable nouns [U] as well as those cases where they can also be used as countable [C] and there are several pictures (a horse s.v. horse and a horse chestnut in one of the illustrated appendices — 1989 edition). The phonetic transcription is based on D. Jones's dictionary and uses the symbols of the International Phonetic Association — again, this sounds commonplace now but it was something really relevant and new at the time.

Another remarkable feature of the first three editions was the classification of verb uses into 25 Verb Patterns, which in the 1974 edition actually become 51 if sub-patterns (e.g. 12A, 12B, 12C, etc.) are counted. On the one hand, this system of numbers and letters allows a high degree of precision in informing about the structural patterns that are admissible for each verb; thus, for example, double transitive verbs belong to VP12A if the indirect object corresponds to a prepositional object with to (He gave me the news Û He gave the news to me), to VP12B if the indirect object corresponds to a prepositional object with for (She bought her daughter a skirt Û She bought a skirt for her daughter), and to VP12C if neither conversion is admitted. On the other hand, the system is heavily complex and it requires either a big effort to memorise it or the frequent recourse to the explanatory table.

The 1989 edition classifies 32 Verb Patterns, using sequences of letters chosen in order to facilitate the comprehension of the resulting abbreviations. The patterns are reduced from 51 to 32 partly by eliminating some marginal distinctions (such as the one, mentioned above, between VP12A to and VP12B for) and partly by removing patterns that only apply to a very small number of verbs. In spite of this, new patterns were introduced that had not been highlighted in previous editions; one of these case refers to double transitive verbs:

For years "The Advanced" was the only large dictionary of this type (we emphasise large because the production of innumerable small and/or limited-circulation dictionaries cannot be accounted for). In 1978 Longman brought out their Longman Dictionary of Contemporary English (LDOCE) that shares many features with OALDCE but also introduces important innovations. As mentioned before, the most relevant innovation is the defining vocabulary: a 2000-word lexicon through which all the others are defined. There are some words, however, that cannot be defined adequately without using a word not included in the LDV; in such cases, the extra word:

1) is made evident by the use of small capitals;

2) is, in its turn, defined by using only words in the LDV.

This means that if you know the central meanings of the 2000 words you can understand all the others with a maximum of one intermediate step. The LDOCE, too, uses pictures, charts and graphs.

Another innovation was the use of a system of letters and numbers that aimed at giving unity to the several grammatical aspects. For example, the figure 3 was used for the grammatical label of all the words that can be followed by the to-infinitive, whether they were nouns, verbs, adjectives or anything else. Later editions (1987 and 1995) used different systems, to improve and facilitate the use of the dictionary. Evolution is a common feature of all lexicography and the study of the changes introduced in new editions is often very interesting.

A new generation of dictionaries was born in 1987 with the first edition of COBUILD (COllins Birmingham University International Language Database — notice that D in COBUILD stands for database, not dictionary), the first large monolingual dictionary for foreigners based on a computerised corpus of 20 million words (or, more precisely, tokens or occurrences); the second edition (1995) is based on 200 million tokens — and the "Bank of English" has kept increasing. To give you an idea of how the language is processed in analysing corpora, here follow the KWIC (Key Word In Context) concordances of the types sole, soles and solely; these concordances were drawn up in 1984 when the corpus included "only" 7 ½ million tokens.

These concordances show the keyword at the centre of the line, preceded by 50 characters and with another 50 characters between the beginning of the keyword and the end of the line. This means that parts of words or isolated letters can be found at the beginning and at the end of the line. Here "characters" includes spaces, punctuation marks and other special signs that the program introduces to keep track of new pages, pictures, etc. Many of these signs have been omitted here.

Although a co-text of only 100 characters is very limited, it is usually enough to find out in what sense a given word is used in a sentence.

The listing shows that sole is mostly used as an adjective (67 tokens out of 80, plus a technical usage, referring to a type of insurance, deriving from the adjective); it refers to the bottom part of a foot, a shoe or a sock eight times; finally, it refers to the fish only four times. The concordance reveals that the adjective is frequently preceded by verbs like take or have. Typical nouns following it are charge, concern, function and responsibility.

In order to get rid of the adjectives, the plural form soles was analysed:

Of the 21 occurrences, three must be discarded because they refer to the plural of sol, the currency of Peru. They are printed in italics in the concordance for soles. Of the remaining 18, only one refers to fish, nine refer to shoes (or slippers, or stockings or socks) and eight to feet.

As a consequence, this being the real frequency and importance of the various uses of the word, the COBUILD reverses the traditional order of sub-entries and under sole it deals with the adjective first, then with the sole of your foot or of a shoe or sock, and finally with the fish. A second entry is used for –soled as in rubber-soled shoes.

The fact that the database has increased by one order of magnitude between the first and the second edition is probably responsible for some changes in the entry. The new edition no longer mentions the verb to sole (perhaps because it is so difficult nowadays to get your shoes soled anyway, particularly in some countries), nor the two examples for the fish found in the first edition, one of which mentions a Dover sole, as Dover is the most frequent premodifier in this sense. Instead, there is a cross-reference to lemon sole; however, nothing can be found under lemon.

 The concordance reveals a comparatively high frequency for solely (60 tokens), but no evident differences in meaning: as Prof. Sinclair (COBUILD project co-ordinator and chief editor of the dictionary) commented, "Solely means solely ‘solely'" and accordingly there is a single entry for solely in the dictionary.

Apart from the meaning, some aspects of usage also become evident; for example, solely is frequently preceded by a negative word (not, never, nor), in sentences of the "not only…, but also…" type. And it is most frequently followed by a preposition (at, by, for, from, in, of, to, with). This means that concordances can shed light on the grammatical aspects of vocabulary use.

Accordingly, another new feature in the COBUILD dictionary is an extra column on the right providing information on: grammatical classes; usage; synonyms, hypernyms and antonyms; and, in the new edition, frequency ranks. The extra column minimises the use of special abbreviations and symbols, thus making searches easier and quicker.