Why is a DC to AC inverter called "inverter"?
Origins of the Inverter
  
  David Prince probably coined the term
  inverter. It is unlikely that any living person
  can now , establish with certainty that
  Prince (or anyone else) was the originator
  of this commonly used engineering term.
  However, in 1925 Prince did publish an
  article in the GE Review titled “The Inverter”. His article contains nearly all
  important elements required by modern
  inverters and is the earliest such publication
  to use that term in the open literature.
  
  The idea of using grid control in combination with phase retard to modulate
  AC power originated with others about
  four years earlier. However, Prince appears to have been the individual who
  took Alexanderson’s expression “inverted rectification” and created a single
  English-language word inverter. It conveys the idea of a rectifier except functioning in an inverted mode of operation,
  hence inverter. 


Source: IEE Explore - History of the inverter.