the degree of combining power of an element or radical as shown by the number of atomic weights of a univalent element, e.g. hydrogen, with which the atomic weight of the element will combine or for which it can be substituted or with which it can be compared
a unit of valency
Carbon has four valencies
the ability to form chemical bonds
[late Latin valentia power, capacity, from Latin valent-, valens, present part. of valēre to be strong]