advenedizo

adj. upstart

n. upstart, one who has risen suddenly in rank or status (especially one who does not deserve it, or one who acts self-important once he has achieved it); parvenu, poor person who has become wealthy

= upstart, start-up [startup].
Ex: Otherwise they run the risk of being usurped by upstart local government PR men or newspaper consortia.
Ex: Smart and speedy start-ups blindside mature companies with their inventiveness then grow up into mature companies and are outsmarted in their turn.