Inflection, derivation, open and closed classes

Inflection

Definition

Inflection is the change in one word by which its part of speech (class) remains the same, e.g. [boy] is noun and if we make a little change in it like, [boys] it is also noun.

The part of speech or class remains the same. See examples of inflection in other parts of speech.

Inflection in Noun

boy, boys
foot, feet
man, men
woman, women
examination, examinations

Inflection in Verb

go, went, gone
come, came, come
attend, attended, attended
do, did, done
say, said, said

Inflection in Adjective

few, fewer, fewest
sophisticated, more sophisticated, most sophisticated
small, smaller, smallest
big, bigger, biggest

Inflection in Adverb

delicately, more delicately, most delicately
prominently, more prominently, most prominently

Inflection in Pronoun

he, his, him
she, her
they, them, their
I, me, mine, my
we, our, us

In all the above examples you have seen that we have made changes in different parts of speech but in doing so their class remains the same.

Derivation

Definition

Derivation is different from inflection because it is the change in one word by which its part of speech (class) also changes.

Example

hospital, hospitalize, hospitalization

You have seen that the word [hospital] is noun and when it is changed into [hospitalize] it became verb and in [hospitalization] it is again noun. So such change in the word by which its class or part of speech also changes is called derivation.

Other examples

advise (verb), advice (noun)
philosophy (noun) philosophical (adjective), philosophically (adverb), philosophize (verb)
psychology (noun), psychological (adjective), psychologically (adverb)
neurology (noun), neurological (adjective), neurologically (adverb)

Open and closed classes

Class is the other name for part of speech.

Open classes

Open classes or open parts of speech are those in which inflection and derivation is possible. All the above examples of inflection and derivation are the examples of open classes. They are; noun, pronoun, verb, adjective, adverb and preposition.

Closed classes

Closed classes are those parts of speech in which inflection or derivation is not possible. For example in preposition, conjunction (subordinator, coordinator) and articles we cannot make any changes.

Some more examples of open classes

Inflection: mountain, mountains

Derivation: simple (adjective), simplification (noun)

Example of closed classes

We cannot make any change in articles (the, an, a), prepositions (to, on, of, at, in etc), and in conjunctions (but, and, also etc).