Regular and irregular verbs


A regular verb is any verb whose conjugation follows the typical pattern, or one of the typical patterns, of the language to which it belongs. A verb whose conjugation follows a different pattern is called an irregular verb..
In English, for example, verbs such as play, enter, and like are regular since they form their inflected parts by adding the typical endings -s, -ing and -ed to give forms such as plays, entering, and liked. On the other hand, verbs such as drink, hit and have are irregular since some of their parts are not made according to the typical pattern: drank and drunk ; hit and has and had.
The classification of verbs as regular or irregular is to some extent a subjective matter. If some conjugational paradigm in a language is followed by a limited number of verbs, or it requires the specification of more than one principal part, views may differ as to whether the verbs in question should be considered irregular. Most inflectional irregularities arise as a result of series of fairly uniform historical changes so forms that appear to be irregular from a synchronic point of view may be seen as following more regular patterns when the verbs are analyzed from a diachronic viewpoint.

Development

When a language develops some type of inflection, such as verb conjugation, it normally produces certain typical patterns by which words in the given class come to make their inflected forms. The language may develop a number of different regular patterns, either as a result of conditional sound changes which cause differentiation within a single pattern, or through patterns with different derivations coming to be used for the same purpose. An example of the latter is provided by the strong and weak verbs of the Germanic languages; the strong verbs inherited their method of making past forms from Proto-Indo-European, while for the weak verbs a different method developed.
Irregularities in verb conjugation may arise in various ways. Sometimes the result of multiple conditional and selective historical sound changes is to leave certain words following a practically unpredictable pattern. This has happened with the strong verbs in English; patterns such as sing–sang–sung and stand–stood–stood, although they derive from what were more or less regular patterns in older languages, are now peculiar to a single verb or small group of verbs in each case, and are viewed as irregular.
Irregularities may also arise from suppletion – forms of one verb may be taken over and used as forms of another. This has happened in the case of the English word went, which was originally the past tense of wend, but has come to be used instead as the past tense of go. The verb be also has a number of suppletive forms – this is common for copular verbs in Indo-European languages.
The regularity and irregularity of verbs is affected by changes taking place by way of analogy – there is often a tendency for verbs to switch to a different, usually more regular, pattern under the influence of other verbs. This is less likely when the existing forms are very familiar through common use – hence among the most common verbs in a language there is often a greater incidence of irregularity.

Types of pattern

The most straightforward type of regular verb conjugation pattern involves a single class of verbs, a single principal part, and a set of exact rules which produce, from that principal part, each of the remaining forms in the verb's paradigm. This is generally considered to be the situation with regular English verbs – from the one principal part, namely the plain form of a regular verb, all the other inflected forms can be derived by way of consistent rules. These rules involve the addition of inflectional endings, together with certain morphophonological rules about how those endings are pronounced, and certain rules of spelling. Verbs which in any way deviate from these rules are classed as irregular.
A language may have more than one regular conjugation pattern. French verbs, for example, follow different patterns depending on whether their infinitive ends in -er, -ir or -re. A verb which does not follow the expected pattern based on the form of its infinitive is considered irregular.
In some languages, however, verbs may be considered regular even if the specification of one of their forms is not sufficient to predict all of the rest; they have more than one principal part. In Latin, for example, verbs are considered to have four principal parts. Specification of all of these four forms for a given verb is sufficient to predict all of the other forms of that verb – except in a few cases, when the verb is irregular.
To some extent it may be a matter of convention or subjective preference to state whether a verb is regular or irregular. In English, for example, if a verb is allowed to have three principal parts specified, then the number of irregular verbs will be drastically reduced. The situation is similar with the strong verbs in German. In French, what are traditionally called the "regular -re verbs" are not in fact particularly numerous, and may alternatively be considered to be just another group of similarly behaving irregular verbs. The most unambiguously irregular verbs are often very commonly used verbs such as the copular verb be in English and its equivalents in other languages, which frequently have a variety of suppletive forms and thus follow an exceptionally unpredictable pattern of conjugation.

Irregularity in spelling only

It is possible for a verb to be regular in pronunciation, but irregular in spelling. Examples of this are the English verbs lay and pay. In terms of pronunciation, these make their past forms in the regular way, by adding the sound. However their spelling deviates from the regular pattern: they are not spelt "layed" and "payed", but laid and paid. This contrasts with fully regular verbs such as sway and stay, which have the regularly spelt past forms swayed and stayed. The English present participle is never irregular in pronunciation, with the exception that singeing irregularly retains the e to distinguish it from singing.

Linguistic study

In linguistic analysis, the concept of regular and irregular verbs commonly arises in psycholinguistics, and in particular in work related to language acquisition. In studies of first language acquisition, one debate among 20th-century linguists revolved around whether small children learn all verb forms as separate pieces of vocabulary or whether they deduce forms by the application of rules. Since a child can hear a regular verb for the first time and immediately reuse it correctly in a different conjugated form which he or she has never heard, it is clear that the brain does work with rules; but irregular verbs must be processed differently. A common error for small children is to conjugate irregular verbs as though they were regular, which is taken as evidence that we learn and process our native language partly by the application of rules, rather than, as some earlier scholarship had postulated, solely by learning the forms. In fact, children often use the most common irregular verbs correctly in their earliest utterances but then switch to incorrect regular forms for a time when they begin to operate systematically. That allows a fairly precise analysis of the phases of this aspect of first language acquisition.
Regular and irregular verbs are also of significance in second language acquisition, and in particular in language teaching and formal learning, where rules such as verb paradigms are defined, and exceptions need to be listed and learned explicitly. The importance of irregular verbs is enhanced by the fact that they often include the most commonly used verbs in the language.
In historical linguistics the concept of irregular verbs is not so commonly referenced. Since most irregularities can be explained by processes of historical language development, these verbs are only irregular when viewed synchronically; they often appear regular when seen in their historical context. In the study of Germanic verbs, for example, historical linguists generally distinguish between strong and weak verbs, rather than irregular and regular.
When languages are being compared informally, one of the few quantitative statistics which are sometimes cited is the number of irregular verbs. These counts are not particularly accurate for a wide variety of reasons, and academic linguists are reluctant to cite them. But it does seem that some languages have a greater tolerance for paradigm irregularity than others.

By language

English

With the exception of the highly irregular verb be, an English verb can have up to five forms: its plain form, a third person singular present tense, a past tense, a past participle, and the -ing form that serves as both a present participle and gerund.
The rules for the formation of the inflected parts of regular verbs are given in detail in the article on English verbs. In summary they are as follows:
The irregular verbs of English are described and listed in the article English irregular verbs. In the case of these:
Some examples of common irregular verbs in English, other than modals, are:
For regular and irregular verbs in other languages, see the articles on the grammars of those languages. Particular articles include, for example:
Some grammatical information relating to specific verbs in various languages can also be found in Wiktionary.

Constructed languages

Most natural languages, to different extents, have a number of irregular verbs. Artificial auxiliary languages usually have a single regular pattern for all verbs as a matter of design, because inflectional irregularities are considered to increase the difficulty of learning and using a language. Other constructed languages, however, need not show such regularity, especially if they are designed to look similar to natural ones.