The degree of combining power of an atom (or radical) as shown by the number of atoms of hydrogen (or of other monads, as chlorine, sodium, etc.) with which it will combine, or for which it can be substituted, or with which it can be compared; thus, an atom of hydrogen is a monad, and has a valence of one; the atoms of oxygen, nitrogen, and carbon are respectively dyads, triads, and tetrads, and have a valence respectively of two, three, and four.
- Chemistry The combining capacity of an atom or radical determined by the number of electrons that it will lose, add, or share when it reacts with other atoms.
- Chemistry A positive or negative integer used to represent this capacity: The valences of copper are 1 and 2.
- The number of binding sites of a molecule, such as an antibody or antigen.
- The ability of a substance to interact with another or to produce an effect.
- Psychology The degree of attraction or aversion that an individual feels toward a specific object or event.
- Linguistics The number 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: "I do not claim to know much more about novels than the writing of them, but I cannot imagine one set in the breathing world which lacks any moral valence” ( Robert Stone).