Depending on affixation and how affixes are separated within a word we distinguish three language types: agglutinating, isolating and fusional.
Agglutinative languages add affixes to the word stem and these affixes are easily distinguishable most of the time. These languages include Turkish, Hungarian, Finnish, Japanese, Korean, etc. By adding several affixes to the stem, you can end up with really long words like the Hungarian legeslegmegszentségteleníttethetetlenebbjeitekként which means “like the most of most undesecratable ones of you”.
Affixation does not really occur in an isolating language, however. The words have only one form so they by themselves form the smallest units of the language, the morphemes. Vietnamese, Chinese and mostly English are examples of this category.
Fusional languages also have affixes but they are harder or impossible to distinguish within a word, they “fuse” with it. Some of the fusional languages are Greek, Latin, Polish, Spanish, Russian, German, etc.
Let’s take a closer look at the differences between these languages through an example sentence:
I did not talk.
The isolating English has separate words to mark person (I) and time (did). The verb doesn’t have any affix attached to it, nor is it different from its infinitive form (talk).
In the agglutinating Hungarian the entire sentence is only two words:
Not talk|(past tense)|(first person singular suffix)
The affixes are easily distinguishable. There is the verb (beszél), then the affix that marks the past tense (t) which together make beszélt (talked) and another affix with the person (em) > beszéltem (I talked).
In Spanish the idea is similar, but the affix for the past tense and person are not separate, they are fused:
Not talk|(first person singular past tense suffix)
Of course, languages don’t exclusively fall into one or another of these categories. The English word unfaithfulness shows agglutination with its 4 affixes: un-, that negates or causes deprivation, hence the name, privative affix, -ful converts the noun faith into an adjective and -ness converts the adjective into a noun.
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