What actually is a vinaigrette ?

According to The Larousse Gastronomique ( one of the well known authorities on French recipes)
is :
"Vinaigrette. A cold sauce made from a mixture of vinegar, oil, salt and pepper to which various flavourings may be added.....
Vinaigrette is used especially for dressing green salads.... It is considered to be a typically French sauce and is often called
"French dressing" in Britain.