We have:

  

 1) the term "ambient", indisputably coined by Eno

 2) the general style "ambient", indeed arguably coined by Satie (though one might suggest that Debussy and the other more mainstream impressionists had something to do with it). There's also works like "in a Landscape" by John Cage (for piano) that clearly predate Eno's work but embody most of the same elements.

 3) Harold Budd, who didn't like the term "ambient" and didn't want his music labelled that way