The traditional morphological typology dates back to the nineteenth century. It distinguishes three language types, i.e., isolating, agglutinative, and fusional languages (Whaley, 1997). This typology was later supplemented by the fourth language type, polysynthetic languages, specifically to explain the morphology of some native American languages. The four morphological types are ideal types rather than practical categories. There are languages that are close to some ideal type, e.g., Chinese and Vietnamese (isolating languages) and Turkish (an agglutinative language). Most languages, however, are mixed types sharing features of different ideal types.
Isolating languages have no morphology at all. The correspondence between words and morphemes is one-to-one. In Vietnamese words appear in the same invariable forms independent of their grammatical functions. This is shown in the following sentence (Comrie, 1989):
Khi toi den nha ban toi, chung toi bat dau lam bai
'When I come house friend I ’plural’ I begin do lesson' (begin = bat dau)
’When I came to my friend’s house, we began to do lessons.’
In agglutinative languages, the boundaries separating one morpheme from another in a word are clear-cut, and morphemes are easily segmentable. In inflection affixes are added to invariable word stems. A classic example is Turkish. The Turkish word form köpekleri can be analyzed into the following morphemes: köpek ('dog'), ler (plural suffix), i (accusative suffix).
In fusional languages, there are no clear-cut boundaries between the morphemes in a word. A monomorphemic word may consist of two or more meaning units. Typical examples of fusional words are the strong verbs of Germanic languages. For instance, the monomorphemic word "took" in English denotes two things, that is, the meanings ’to take’ and ’past tense’.
In polysynthetic languages, a word may consist of a large number of lexical and bound morphemes. A word consisting of several morphemes may form an entire sentence. Thus the difference between a word and a sentence is sometimes obscure in polysynthetic languages. The Inuit (Eskimo) language is often regarded as a typical polysynthetic language.
Most of the world’s languages are mixed types. For instance, in English grammatical relations are shown mainly by means of prepositions. This resembles the pattern of isolating languages. The derivational and inflectional morphologies of English are in part agglutinative and in part fusional. For instance, the word fortunate (fortune + ate) is fusional. The form fortunately (fortunate + ly) is agglutinative.
Table 1
presents examples of agglutinative and fusional words. The examples are from
English (inflection and derivation) and Swedish (compounds). Swedish is a
language with a high frequency of compounds. The cases of "house" + s =>
"houses", "read" + er => "reader", and "järn" + "industri" =>
"järnindustri" represent agglutination. No structural changes occur when
the affixes s and er are attached into the word stems house and read. The
compound word "järnindustri" is formed in the same way without structural
changes. The words "distributing" (distribute + ing), "cylindrical" (cylinder +
ical), and "gatubelysning" (gata + belysning) represent fused words. Now the
product words of morphological processes differ from the cases where the
components were put together as such.
Table 1. Examples of agglutinative and fusional words