<p><strong>Noun</strong></p><ul><li>Valency: the quality that determines the number of atoms or groups with which any single atom or group will unite chemically</li><li>The relative combining capacity of an atom or group compared with that of the standard hydrogen atom</li><li>The chloride ion, Cl–, with a valence of one, has the capacity to unite with one atom of hydrogen or its equivalent, as in HCl or NaCl</li><li>Immunology: the number of determinants per molecule of antigen</li><li>The capacity of one person or thing to react with or affect another in some special way, as by attraction or the facilitation of a function or activity</li></ul>