With regard to cars, homologation usually means that the manufacturer has built enough cars of a certain type to qualify for racing in a league/series that requires cars that have been built as production road cars - not just a purpose-built racecar but something that can be driven on the street. The O in GTO (as in Ferrari GTO) is for Omolagato - or Homologation in Italian. Ferrari built the road-going GTOs in order to qualify the car for entry into certain racing leagues.
