In linguistics and etymology, suppletion is traditionally understood as the use of one word as the inflected form of another word when the two words are not cognate. For those learning a language, suppletive forms will be seen as "irregular" or even "highly irregular".

The term "suppletion" implies that a gap in the paradigm was filled by a form "supplied" by a different paradigm. Instances of suppletion are overwhelmingly restricted to the most commonly used lexical items in a language.

Irregularity and suppletion

An irregular paradigm is one in which the derived forms of a word cannot be deduced by simple rules from the base form. For example, someone who knows only a little English can deduce that the plural of girl is girls but cannot deduce that the plural of man is men. Language learners are often most aware of irregular verbs, but any part of speech with inflections can be irregular.

For most synchronic purposes—first-language acquisition studies, psycholinguistics, language-teaching theory—it suffices to note that these forms are irregular. However, historical linguistics seeks to explain how they came to be so and distinguishes different kinds of irregularity according to their origins.

Most irregular paradigms (like man:men) can be explained by phonological developments that affected one form of a word but not another (in this case, Germanic umlaut). In such cases, the historical antecedents of the current forms once constituted a regular paradigm.

Historical linguistics uses the term "suppletion"^[1] to distinguish irregularities like person:people or cow:cattle that cannot be so explained because the parts of the paradigm have not evolved out of a single form.

Hermann Osthoff coined the term "suppletion" in German in an 1899 study of the phenomenon in Indo-European languages.^[2][3][4]

Suppletion exists in many languages around the world.^[5] These languages are from various language families: Indo-Aryan, Dravidian, Arabic, Romance, etc.

For example, in Georgian, the paradigm for the verb "to come" is composed of four different roots (di-, -val-, -vid-, and -sul-).^[6]

Similarly, in Modern Standard Arabic, the verb jāʾ ("come") usually uses the form taʿāl for its imperative, and the plural of marʾah ("woman") is nisāʾ.

Some of the more archaic Indo-European languages are particularly known for suppletion. Ancient Greek, for example, has some twenty verbs with suppletive paradigms, many with three separate roots.

Example words

To go

In English, the past tense of the verb go is went, which comes from the past tense of the verb wend, archaic in this sense. (The modern past tense of wend is wended.) See Go (verb).

The Romance languages have a variety of suppletive forms in conjugating the verb "to go", as these first-person singular forms illustrate (second-person singular forms in imperative):^[7]

The sources of these forms, numbered in the table, are six different Latin verbs:

1. vādere ‘to go, proceed’,^[8]
2. īre ‘to go’
3. ambitāre ‘to go around’,^[9] also the source for Spanish and Portuguese andar ‘to walk’
4. ambulāre ‘to walk’, or perhaps another Latin root, a Celtic root, or a Germanic root halon or hala^[10]
5. fuī suppletive perfective of esse ‘to be’.^[11]
6. meāre ‘to go along’.

Many of the Romance languages use forms from different verbs in the present tense; for example, French has je vais ‘I go’ from vadere, but nous allons ‘we go’ from ambulare. Galician-Portuguese has a similar example: imos from ire ‘to go’ and vamos from vadere ‘we go’; the former is somewhat disused in modern Portuguese but very alive in modern Galician. Even ides, from itis second-person plural of ire, is the only form for ‘you (plural) go’ both in Galician and Portuguese (Spanish vais, from vadere).

Sometimes, the conjugations differ between dialects. For instance, the Limba Sarda Comuna standard of Sardinian supported a fully regular conjugation of andare, but other dialects like Logudorese do not (see also Sardinian conjugation). In Romansh, Rumantsch Grischun substitutes present and subjunctive forms of ir with vom and giaja (both are from Latin vādere and īre, respectively) in the place of mon and mondi in Sursilvan.

Similarly, the Welsh verb mynd ‘to go’ has a variety of suppletive forms such as af ‘I shall go’ and euthum ‘we went’. Irish téigh ‘to go’ also has suppletive forms: dul ‘going’ and rachaidh ‘will go’.

In Estonian, the inflected forms of the verb minema ‘to go’ were originally those of a verb cognate with the Finnish lähteä ‘to leave’, except for the passive and infinitive.

Good and bad

In Germanic, Romance (except Romanian), Celtic, Slavic (except Bulgarian and Macedonian), and Indo-Iranian languages, the comparative and superlative of the adjective "good" is suppletive; in many of these languages the adjective "bad" is also suppletive.