The Collaborative International Dictionary of English v.0.48:

Roumanian \Rou*ma"ni*an\, a. [Written also Rumanian and
   Romanian.] [From Roumania, the name of the country,
   Roumanian Rom[^a]nia, fr. Rom[^a]n Roumanian, L. Romanus
   Roman.]
   Of or pertaining to Roumania.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Roumanian \Rou*ma"ni*an\, n.
   An inhabitant of Roumania; also, the language of Roumania,
   one of the Romance or Romanic languages descended from Latin,
   but containing many words from other languages, as Slavic,
   Turkish, and Greek. [Written also Rumanian and Romanian.]
   [Webster 1913 Suppl.] Roun

WordNet (r) 3.0 (2006):

Rumanian
    adj 1: of or relating to or characteristic of the country of
           Romania or its people or languages; "Romanian folk music"
           [syn: Romanian, Rumanian, Roumanian]
    n 1: an eastern Romance language spoken in Romania [syn:
         Romanian, Rumanian]
    2: a native or inhabitant of Romania [syn: Romanian,
       Rumanian]