An Etymological Dictionary of Astronomy and Astrophysics

A measure of the number of chemical bonds formed by the atoms of a given element. It represents the relative ability of an atom of an element to combine with other atoms. For example, the valence of O in water, H₂O, is 2.
Also called valency.

Etymology (EN): M.E., from O.Fr., from L valentia “strength, worth,” from valentem (nominative valens), pr.p. of valere “to be strong.”

Etymology (PE): Arzâyi, noun from arzâ, agent noun/adj. from arzidan “to be worth,” arzân “worthy; of small value, cheap,” arj “esteem, honour, price, worth” (Mid.Pers. arz “value, worth,” arzidan “be worth,”
arzân “valuable;” Av. arəjaiti “is worth,” arəja- “valuable,” arəg- “to be worth;” cf. Skt. arh- “to be worth, to earn,” árhant- “worthy person;” Gk. alphanein “to bring in as profit,” alphein “to ear, obtain;” Lith. algà “salary, pay;” PIE base *alg^wh- “to earn; price, value”).