e·quiv·a·lent / iˈkwivələnt/ • adj. equal in value, amount, function, meaning, etc.: one unit is equivalent to one glass of wine. ∎  (equivalent to) having the same or a similar effect as: some regulations are equivalent to censorship. ∎  Math. belonging to the same equivalence class.• n. a person or thing that is equal to or corresponds with another in value, amount, function, meaning, etc.: the French equivalent of the FBI. ∎  (also equivalent weight) Chem. the mass of a particular substance that can combine with or displace one gram of hydrogen or eight grams of oxygen, used in expressing combining powers, esp. of elements.DERIVATIVES: e·quiv·a·lence n.e·quiv·a·lent·ly adv.

equivalent adj. XV; sb. XVI. — (O)F. équivalent — prp. of late L. æquivalēre, f. æqui- EQUI- + valēre be worth.
So equivalence, equivalency XVI.