The world 'Definitive' as used in the passage means _________.

Read the following passage & answer the questions that follow:
The last half of my life has been lived in one of those painful epochs of human history during which the world is getting worse, and past victories which had seemed to be definitive have  turned out to be only temporary.

When I was young, Victorian optimism was taken for granted. It was thought that freedom & prosperity would speed gradually throughout the world by an orderly process, & it was hoped that cruelty, tyranny, and injustice would continually diminish. Hardly anyone was haunted by the fear of great wars. Hardly anyone thought of the of the nineteenth century as a brief interlude between past and future barbarism.