"things desired or desirable, that which is lacking or required," 1650s, plural of desideratum, Latin, literally "something for which desire is felt," noun use of neuter past participle of desiderare "to long for" (see desire (v.)).
A Latin word in English; other offshoots of the Latin verb were nativized in Middle English: desiderable "wished for, desired" (mid-14c.), also "worthy of being admired;" desideracioun "longing, yearning" (late 15c.); desiderantly "with ardent desire" (c. 1500). Also compare obsolete desiderate "feel a desire or longing for" (1640s).