1. Not possible to classify

See also: unidentifiable

• Royal Academy
• Royal Academy of Arts
• royal agaric
• Royal Air Force
• royal blue
• royal brace
• Royal Canadian Mounted Police
• royal casino
• royal charter
• royal court
• royal family
• royal fern
• royal flush
• royal house
• royal icing
• royal jelly
• royal line
• royal mast
• Royal National Eisteddfod
• royal osmund
• royal palm
• royal poinciana
• royal purple
• royal road
• Royal Society