Copula (noun)

1. A linking verb that connects the subject of a sentence to a subject complement.
2. A verb that serves to link the subject of a sentence to a subject complement and shows the relationship between the two.
3. A word that serves to link the subject of a sentence to a subject complement and indicates the relationship between the two, such as 'be', 'seem', 'appear', 'become', etc.

Origin:

From the latin word 'copula' meaning 'link or bond'.

Examples:

1. The copula 'be' is used to describe the identity of the subject.
2. The copula 'seem' is used to describe the appearance or impression of the subject.
3. The copula 'become' is used to describe a change in the subject.
4. The copula 'appear' is used to describe the subjective perception of the subject.
5. The use of copulas is an important aspect of English grammar.