Zero (linguistics)

• In phonetics, a null phoneme or zero phone indicates that no phone is produced where one might be expected. For example, in syllable structure analysis, null onset indicates that a syllable lacks an initial consonant that is normally required by phonotactics of the considered language. For an example, see Standard Chinese phonology#Zero onset.
• In morphology, a zero morph, consisting of no phonetic form, is an allomorph of a morpheme that is otherwise realized in speech. In the phrase two sheep-∅, the plural marker is a zero morph, which is an allomorph of -s as in two cows. In the phrase I like-∅ it, the verb conjugation has a zero affix, as opposed to the third-person singular present -s in he likes it.
• Similarly, a zero inflection is an unrealized inflection, such as in nouns with identical singular and plural forms. For example, plural of sheep can be analyzed as sheep-∅.
• In grammar, a zero pronoun occurs in some languages. In the English sentence nobody knows ∅ the zero pronoun plays the role of the object of the verb, and in ∅ makes no difference it plays the role of the subject. Likewise, the zero pronoun in the book ∅ I am reading plays the role of the relative pronoun that in the book that I am reading. In generative grammar, this is also referred to as PRO. In pronoun-dropping languages, including null subject languages such as most Romance languages, the zero pronoun is a prominent feature.
• A zero subordinate conjunction occurs in English in sentences like I know ∅ he likes me, in which the zero conjunction plays the role of the subordinate conjunction that in I know that he likes me. This comes naturally to native speakers of English, but some non-native learners of English have to consciously adjust to it, as their native languages rarely do it.
• A zero article is an unrealized indefinite or definite article in some languages, such as the plural indefinite article in English.
• A zero copula, in which a copula such as the verb to be is implied but absent. For example, in Russian the copula is usually omitted in the present tense, as in "Она красивая", the same happening with colloquial Brazilian Portuguese, as in "irônicos, aqueles", though never with the adjective coming after the subject as usual in Romance languages. In English the copula is sometimes omitted in some nonstandard dialects.