In
morpheme-based morphology, a 'null morpheme' is a
morpheme that is realized by a
phonologically null
affix (an empty string of phonological segments). In simpler terms, a null morpheme is an "invisible" affix. It's also called 'zero morpheme'; the process of adding a null morpheme is called ''null affixation'', ''null derivation'' or ''zero derivation''. The concept was first used over two thousand years ago by
PÄṇini in his
Sanskrit grammar. (Some linguists object to the notion of a null morpheme, since it sets up (they say) an unverifiable distinction between a "null" or "zero" element, and nothing at all.)
The null morpheme is represented as either the figure zero (''0''), the
empty set symbol ø, or its variant Ø.
Examples in English include
hiatus and co-operation.
The existence of a null morpheme in a
word can also be theorized by contrast with other forms of the same word showing alternate morphemes. For example, the singular number of
English nouns is shown by a null morpheme that contrasts with the plural morpheme ''-s''.
★ ''cat'' = ''cat'' + ''-Ø'' = ROOT ("cat") + SINGULAR
★ ''cats'' = ''cat'' + ''-s'' = ROOT ("cat") + PLURAL
In addition, there are some cases in English where a null morpheme indicates plurality in nouns that take on irregular plurals.
★ ''sheep'' = ''sheep'' + ''-Ø'' = ROOT ("sheep") + SINGULAR
★ ''sheep'' = ''sheep'' + ''-Ø'' = ROOT ("sheep") + PLURAL
Also, a null morpheme marks the present tense of
verbs in all forms but the third person singular:
★ ''(I) run'' = ''run'' + ''-Ø'' = ROOT ("run") + PRESENT: Non-3rd-SING
★ ''(He) runs'' = ''run'' + ''-s'' = ROOT ("run") + PRESENT: 3rd-SING
According to some linguists' view, it's also a null morpheme that turns some English
adjectives into verbs of the kind of ''to clean, to slow, to warm''. Null derivation, also known as
conversion if the
word class changes, is very common in English.
In
languages that show the above distinctions, it's quite common to employ null affixation to (not) mark singular number, present tense and third persons (English is unusual in its marking of the third person singular with a non-zero morpheme, by contrast with a null morpheme for others). It's also frequent to find null affixation for the least-
marked cases (the
nominative in
nominative-accusative languages, and the
absolutive in
ergative-absolutive languages).
A basic radical element plus a null morpheme is not the same as an
uninflected word, though usage may make those equal in practice.
See also
★
Linguistics
★
Morphology (linguistics)
★
Uninflected word
★
Affix
★
Zero (linguistics)
★
Marker (linguistics)
★
Lemma (linguistics)
★
Hiatus (linguistics)