valence

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. 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.
2. n. Chemistry A positive or negative integer used to represent this capacity: The valences of copper are 1 and 2.
3. n. The number of binding sites of a molecule, such as an antibody or antigen.
4. n. The ability of a substance to interact with another or to produce an effect.
5. n. Psychology The degree of attraction or aversion that an individual feels toward a specific object or event.
6. n. 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.
7. n. 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).

Century Dictionary and Cyclopedia

1. See valance.
2. n. 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. The original statement of the law of valence was that each atom could combine with a certain definite number of hydrogen atoms, or with an equivalent number of atoms of any other element, and that this number was fixed and unalterable. This number expressed the valence, which was a constant, an invariable property of the element. For example, one atom of phosphorus combines with three atoms of chlorin, forming phosphorus trichlorid. As the chlorin atom is univalent, phosphorus appears to be trivalent. But in phosphorus pentachlorid one atom of phosphorus combines with five of chlorin, and therefore phosphorus in this case appears quinquivalent. In view of facts like these it is held by some authorities that the valence of an element is a varying quality depending on the nature of the other combining atoms, temperature, etc. By others valence is assumed to be invariable, but the total valence is not always exhibited or in force. Also called valency, equivalence, and, less properly, atomicity.
3. n. In biology: Form value; morphological value or equivalency. See morphic.
4. n. In zoology, taxonomic value or equivalency; classificatory grade or rank of a zoölogical group.

Wiktionary

1. n. chemistry, obsolete An extract; a preparation.
2. n. chemistry The combining capacity of an atom, radical or functional group determined by the number of electrons that it will lose, gain, or share when it combines with other atoms etc
3. n. chemistry The number of binding sites of a molecule, such as an antibody or antigen
4. n. linguistics The number of arguments that a verb can have, including the subject of the verb in the counting, ranging from zero (for the likes of "It rains") to three (for the likes of "He gives her a flower").
5. n. psychology A one-dimensional value assigned to an object, situation, or state, that can usually be positive or negative
6. n. sociology value
7. n. alternative spelling of valance.

GNU Webster's 1913

1. n. (Chem.) 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.

WordNet 3.0

1. n. (biology) a relative capacity to unite or react or interact as with antigens or a biological substrate
2. n. (chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent)