Emily Dickinson Lexicon

DE-SID-ER-A'TUM, n. [plur. desiderata; L. desideratus, – um, from desidero, to desire.]

That which is desired; that which is not possessed, but which is desirable; any perfection or improvement which is wanted. The longitude is a desideratum in navigation. A tribunal to settle national disputes without war is a great desideratum.