(chem) a property of atoms or groups, equal to the number of atoms of hydrogen that the atom or group could combine with or displace in forming compounds
2.
(linguistics) the number of satellite noun phrases with which a verb combines: the English verb `give' takes a subject and two objects, so it has a valency of three
3.
(immunol)
the number of antigen-binding sites on an antibody molecule
the number of antigen-binding sites with which an antigen can combine
Word Origin
C19: from Latin valentia strength, from valēre to be strong