Traditional definitions of parts of speech based on meaning are criticized by linguists. Notional definitions assume a direct link between grammatical form and semantic meaning, but the relationship is complex. For example, "rejection" and "rejected" have similar meanings but different grammatical functions. Satisfactory definitions must identify grammatical properties that distinguish parts of speech. Words are classified according to their properties in phrases and clauses, not their meanings. Parts of speech fall into closed classes that are finite and stable, or open classes that constantly change.

2. Traditional notional definitions of
parts of speech
Definitions based on the meaning of the expressions
being classified, not on their grammatical properties.
E.g., the notional definition of the noun and verb =
nouns name persons, places and things; verbs are
concerned with describing the action or state, i.e.
with ‘doing things’.
E.g., to determine whether a word is a noun, one asks
what it means or denotes; to determine the tense of a
verb, one asks in what time period it locates the
action or state expressed by the verb, etc.

3. Traditional notional definitions of
parts of speech
Traditional definitions – criticised by linguists
Ex., traditionally, preterite is defined as a tense
expressing past action or state:
1. (a) The finals started yesterday.
(b) You said the finals started tomorrow.
2. (a) I gave them his address.
(b) I regret giving them his address.
The notional definition gives the wrong results in
both the (b) examples.

4. Traditional notional definitions of
parts of speech
Definitions are supposed to give necessary and sufficient
conditions for belonging to some category, and the
notional definitions for the preterite given above fails
completely.
(1b) shows that past time reference is not necessary for a
word to be a preterite verb form, and (2b) shows that it is
not sufficient either.
The problem is that the relation between the grammatical
category of tense (form) and the semantic category of time
(meaning) is highly complex, and the notional definition
assumes that the form can be defined directly in terms of
meaning.

5. Traditional notional definitions of
parts of speech
The traditional definition of noun – also
unsatisfactory.
The problem – the concept of ‘thing’, or ‘name’, is too
vague to provide a workable criterion.
E.g. there are many abstract nouns such as absence,
fact, flaw, idea, indeterminacy, lack, necessity, etc., so
‘thing’ cannot be intended as equivalent to ‘physical
object’.

6. Traditional notional definitions of
parts of speech
3. (a) I was annoyed at their rejection of my proposals.
(b) I was annoyed that they rejected my proposals.
These sentences have essentially the same meaning, but
rejection is a noun, and rejected a verb.
These two words figure in quite different grammatical
constructions.
E.g. rejection vs. rejections
E.g. rejected vs. reject
E.g., transitive verbs like reject take a direct object, while
nouns do not.
E.g., rejected takes a nominative subject (they), rejection
takes a determiner like possessive their.

7. Grammatical criteria for defining
parts of speech (word classes)
A satisfactory definition or explanation of concepts
like noun or preterite must identify grammatical
properties that distinguish them from the concepts
with which they contrast.
The discussion of rejection and rejected illustrated
some of the major ways in which nouns differ from
verbs.
We assign words to their various classes on
grammatical grounds, i.e. according to their
properties in entering phrasal and clausal structure.

8. Grammatical criteria for defining
parts of speech (word classes)
E.g., determiners (the, a , that, etc.) link up with
nouns to form noun phrases as in a girl;
Pronouns can replace noun phrases as in “I saw a girl
and I asked her the time.”

9. Closed and open word classes
Words fall into two broad categories: closed and
open.
The category of closed word classes comprises classes
that are finite (and often small) with a relatively
stable and unchanging membership.
Words that belong to closed classes play a major part
in English grammar, and often correspond to
inflections in some other languages. They are
sometimes referred to as ‘grammatical words’,
‘structure words’, or ‘function words’.

10. Closed and open word classes
The open classes of words are constantly changing
their membership as old words drop out of the
language and new ones are coined or adopted to
reflect cultural changes in society. They are often
called ‘lexical words’.

11. Closed classes
Pronoun: she, they, anybody, etc.
Determiner: the, a , some, those, etc.
Primary verb: be, have, do
Modal auxiliary verb: can, may, shall, will, must, etc.
Preposition: in, during, round, etc.
Conjunction: and, or, while, yet, etc.

12. Open classes
Noun: girl, idea, table, Gloria, etc.
Adjective: sufficient, happy, round, etc.
Full lexical verbs: grow, play, interrogate, etc.
Adverb: sufficiently, really, afterwards, yet, etc.

13. Other categories of words
Numerals: three, sixty-five, etc.
Interjections: oh, wow, etc.
A word may belong to more than class, like for
example round
E.g. Drive round the corner. round = preposition