valence

The combining capacity of an atom or group of atoms as determined by the number of electrons it can lose, add, or share when it reacts with other atoms or groups.

An integer used to represent this capacity, which may be given as positive or negative depending on whether electrons are lost or gained, respectively.

The number of binding sites of a molecule, such as an antibody or antigen.

The number of different antigens contained in a vaccine, corresponding to the number of pathogens that it is active against.

The degree of attraction or aversion that an individual feels toward a specific object or event.

The number and type of arguments that a lexical item, especially a verb, can combine with to make a syntactically well-formed sentence, often along with a description of the categories of those constituents. Intransitive verbs (appear, arrive) have a valence of one—the subject; some transitive verbs (paint, touch), two—the subject and direct object; other transitive verbs (ask, give), three—the subject, direct object, and indirect object.

The capacity of something to unite, react, or interact with something else.

In chem., the relative saturating or combining capacity of an atom compared with the standard hydrogen atom; the quality or force which determines the number of atoms with which any single atom will chemically unite.

In biology: Form value; morphological value or equivalency. See morphic.