See AEIOU (disambiguation) for other meanings of AEIOU

AEIOU, or A.E.I.O.U. was a device utilised by the Habsburgs emperors. Emperor Frederick III, who had a fondness for mythical formulae, habitually signed buildings and objects with the acronym. Its original meaning remains unknown, and may have a mythical meaning lost to us today. Later interpretations proceed on the assumption that it was meant as a political slogan:

• Austria est imperio optime unita
• Austria erit in orbe ultima - "Austria will be forever"
• Austriae est imperare orbi universo - "It is Austria's destiny to rule the world"
• Alles Erdreich ist Österreich untertan - (16th/17th century) "The world is subject of Austria's rule" Both these versions refer not to the small Austria of today, but the huge Habsburg empire where "the sun did not set".

In 1951 Eugen Rosenstock-Huessy (1888-1973) suggested the interpretation: Austria Europae Imago, Onus, Unio - "Austria is Europe's spitting image, burden and unification".

The Austrian ministry of education, science and culture runs a web-based culture information system under the name "AEIOU, the Austrian cultural information system of the Federal Ministry for Education, Science and Culture".