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The
formal criterion provides for the exposition of the
specific inflexional and derivational (word-building) features of
words of a part of speech and deals with the morphological
properties of words, which include: 1) the system of inflexional
morphemes of words, typical of a certain part of speech; 2) the
system
of
derivational
lexico-grammatical
morphemes,
characteristic of a part of speech.
Each part of speech is characterized by its grammatical
categories, manifested in the paradigms of lexemes (e.g. nouns –
have the categories of number and case; verbs – have the
categories of mood, tense, aspect, voice, person, number;
adjectives – have the category of degrees of comparison). Thus,
the paradigms of words, belonging to different parts of speech are
different and these paradigms show to what part of speech the
word belongs.
As words of different classes are also characterized by a
specific system of derivational morphemes, the presence of a
certain lexico-grammatical morpheme in
the word signals its part
of speech reference. Many of these derivational morphemes are
regularly used to form the words of a part of speech, other stem-
building elements are of little significance as distinctive features
of a part of speech because they are not systematic and may be
found within separate lexemes of a class (e.g. : food – feed;
blood-bleed; full – fill). Thus, the morphological composition or
stem- structure is one of the criteria employed for part of speech
classification but it cannot function separately in order to
classify words. Many English words of different classes consist
only of roots and have no derivational morphemes in their
structure.
The
functional criterion concerns the syntactic properties
of a part of speech, which are of two kinds:
combinability and
syntactic functions in the sentence. The
combinability is the ability
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of words of a given part of speech to be in syntactic connection
with other words in the sentence. A word has different syntactic
connections.
These connections are not equally significant for parts of
speech reference. But the connection of the noun with the verb is
less significant than its connection with the adjective. Owning to
the lexico-grammatical meaning of nouns (substance) and
prepositions (relation to substance) these two
parts of speech often
form up word combinations. The article is characterized by
unilateral right- hand connections with different classes of words.
Thus, the combinability of a word, its connections in speech help
to show to what part of speech it belongs. Parts of speech
perform
certain syntactic functions in the sentence: nouns – of the subject
and object, verbs – of predicates; adjectives – attributes) but the
subject may be expressed not only by nouns and nouns can
perform practically all syntactic functions. Thus, due to the little
significance of the syntactic function of a word in identifying its
class reference, this criterion is the least helpful.
None of the above mentioned criteria is sufficient to be an
absolute principle of word discrimination. Only all of them taken
together give a fully satisfactory basis for part of speech
classification. Thus, a part of speech is a set of words
characterized by identical properties: 1) general grammatical
meaning; 2) lexico- grammatical morphemes (derivational or stem-
building); 3) grammatical categories; 4) combinability; 5)
functions in the sentence. As the dominant criteria in parts of
speech classification are grammatical, it is reasonable to refer to
word classes, traditionally called ―parts of speech‖ as grammatical
word classes.