Permaculture is a concept integrating an ecological approach to all aspects of human endeavors. It is a design system for sustainability encompassing agriculture, building, living and other aspects of human activities, drawing connections and relations with the ecological system as a whole. It is a portmanteau of permanent culture as well as a permanent agriculture. Its basic principles were established in the 1970s by Australians Bill Mollison and David Holmgren.
Kim Stanley Robinson is a promoter of permaculture and has mentioned it repeatedly in interviews and in his works. He also sees it as a portmanteau of permutable culture as the concept would not imply a steady state but an ever-evolving culture that conserves sustainability in its core principles.
For example, from Sixty Days And Counting (Phil Chase's blog, p.479):
That's what we're doing in history; call it the invention of permaculture. By permaculture I mean a culture that can be sustained permanently. Not unchanging, that's impossible, we have to stay dynamic, because conditions will change, and we will have to adapt to those new conditions, and continue to try to make things even better - so that I like to think the word permaculture implies also permutation. We will make adaptations, so change is inevitable.
In a 2007 interview (BLDBLOG interview):
But if you think of yourself as terraforming Earth, and if you think about sustainability, then you can start thinking about permaculture and what permaculture really means. It’s not just sustainable agriculture, but a name for a certain type of history. [...] I’ve been working all my career to try to redefine utopia in more positive terms – in more dynamic terms. People tend to think of utopia as a perfect end-stage, which is, by definition, impossible and maybe even bad for us. And so maybe it’s better to use a word like permaculture, which not only includes permanent but also permutation. Permaculture suggests a certain kind of obvious human goal, which is that future generations will have at least as good a place to live as what we have now.
Permaculture on Wikipedia
The Permaculture Institute
The Permaculture Activist magazine
Keith Johnson's Permaculture & Regenerative Design blog