Enzymes that utilize NAD+ are often named dehydrogenases.  They are generally named by first naming the substrate upon which they act and then dehydrogenase,  e.g. Lactic acid dehydrogenase would be an enzyme that catalyzes the reaction (oxidation) of lactic acid to pyruvic acid via the loss of hydrogen.  It is often confusing, but the same enzyme also catalyses the reverse reaction but generally bears the name of only one.  The trick becomes in trying to determine for which reaction the enzyme is named.