A copula is a type of obligatory verb or affix that appears in a nonverbal (nominal, adverbial) predicative sentence. In its base form, the copula has no meaning other than its predicative function; if it is an independent word, it is generally the same as the substantive verb ‘be.’ Use of the copula may differ for nonverbal predicates. This parameter is examined in the case of sentences containing nominal or pronominal subjects in the nominative case (or their simplest form) and nominal predicates.

Such sentences are first examined in their base form. This refers to sentences that are a) stative-like[1], b) declarative mood, c) present tense and/or the least marked (most neutral) aspect, and d) appear in third-person singular. These are referred to as unmarked predicative forms. If such sentences include any required items in addition to the subject and adverbial, the language has a copula. If the sentences do not include such required items, sentences with marked predicate forms should be examined instead. If the copula is not found to appear in these cases either, it is likely that the language does not have a copula at all[2]. If it does appear, sentences without a visible copula are considered to have a zero copula.

Types:

NoCop: The language has no copula.

NNoCop: The copula cannot be used with nominal predicates (but is used for adjectival and/or adverbial predicates).[3]

NCopDep: Depending on certain grammatical circumstances, the copula does occur with nominal predicates.[4]

NCop:  Use of the copula with nominal predicates is always required.

When a language displays both NNoCop and NCopNonPres, the two values can be listed with an ampersand (&).

[1] This means that, in present tense or as a general statement, only the predicative function is expressed. Copulative verbs that contain additional information besides their copular function (such as progressiveness, change, or the lack thereof) are not considered to be copulas from a typological point of view, because these verbs can also be found in languages that do not feature a purely predicative form of the copula.

[2] This can be verified if it is also true for the use of a copula with an adjectival or adverbial predicate. See the following parameters: Copula use with an adjectival predicate, Copula use with an adverbial predicate.

[3] With adjectival and/or adverbial predicates (particularly those relating to place or time), copula use is examined in sentences that would otherwise fulfill criteria a) through d). Differences that occur in the case of copula use should be noted in the commentary.

[4] To be specified in the commentary.