desideratum \dih-sid-uh-RAY-tum; -RAH-\ (noun) – Something desired or considered necessary. plural desiderata

“I went, had admittance, and offered him my service as a master of the Greek language, which I had been told was a desideratum in this university.” — Oliver Goldsmith, ‘The Vicar of Wakefield’

Desideratum is from Latin desideratum, “a thing desired,” from desiderare, “to desire.”