The word “Permaculture” was coined in 1978 by Bill Mollison and David Holmgren. It was originally a contraction of “permanent agriculture” but is often now explained as relating to “permanent culture.” Permaculture is an Australian invention but has now spread all around the world.
There are so many definitions for Permaculture. Every time I am asked what it is I have to think about it and often come out with a different way of explaining it. I’ve looked around on the web for different ways of describing what it is so that it can be clearly understood by people who don’t know what it is …
‘Permaculture is an ecological design system for sustainability which encompasses all aspects of human endeavour. The philosophy of permaculture is one of working with rather than against nature. It emphasizes protracted and thoughtful observation rather than premature and thoughtless action. Permaculture design techniques encourage ecologically sound land use and apply lessons from nature. The system teaches us to create settings and construct systems which have the diversity, stability, and resilience of natural ecosystems. Permaculture is a way of looking at life and living which incorporates traditional practices with the benefits of modern technology. It creates harmonious relationships between people and the natural environment. Permaculture teaches us how build natural homes, grow our own food, catch rainwater, dispose of waste responsibly, build socially viable communities, restore diminished landscapes and ecosystems, and much more.’
Another definition from Wikipedia …
Permaculture is an approach to designing human settlements and agricultural systems that is modeled on the relationships found in nature. It is based on the ecology of how things interrelate rather than on the strictly biological concerns that form the foundation of modern agriculture. Permaculture aims to create stable, productive systems that provide for human needs; it’s a system of design where each element supports and feeds other elements, ultimately aiming at systems that are virtually self-sustaining and into which humans fit as an integral part.
Permaculture as a systematic method was developed by Australians Bill Mollison and David Holmgren during the 1970s. The word ‘permaculture’ originally referred to ‘permanent agriculture’, but was expanded to also stand for ‘permanent culture’ as it was seen that social aspects were integral to a truly sustainable system. Mollison has described permaculture as ‘a philosophy of working with, rather than against nature; of protracted and thoughtful observation rather than protracted and thoughtless labor; and of looking at plants and animals in all their functions, rather than treating any area as a single project system.’ 
Permaculture draws from several other disciplines including organic farming, agroforestry, sustainable development, and applied ecology. ‘The primary agenda of the movement has been to assist people to become more self reliant through the design and development of productive and sustainable gardens and farms. The design principles which are the conceptual foundation of permaculture were derived from the science of systems ecology and study of pre-industrial examples of sustainable land use.’ 
And one I saw on permies.com that I like …
‘Permaculture – A system giving high yields for low energy inputs, and using ‘only’ God’s intelligent design along with human observation & application to achieve a productive resource of great complexity and stability.’ ~ Jami/Mollison
And probably the most succint explanations I’ve heard recently spoken by one of the legends of Permaculture; Geoff Lawton:
‘It’s a system of design for sustainable living where humanity can provide for all it’s needs in a way that’s beneficial to the environment itself’
If those definitions aren’t enough here are some definitions from the elders of Permaculture.
What does Permaculture mean to me?
For me it means all of the above, but also it’s a real opportunity, to explore how we as humans, instead of being seperate from the earth and bringing degradation and destruction to it, can bring regeneration, stability, balance and sustainability. How WE can get into balance with that in which we are immersed; Nature! How we can find our place within this great eco-system in which we live so that we can live in harmony with that.
For me, this is a worthy endeavor and I feel fortunate that I am on this path.
Some good web sites if you want to know more about Permaculture:
‘Learning to Live Well with the Earth’.
Andrew Faust has a talent for expressing what Permaculture is at it’s deepest level.
An interesting and humorous lecture on ‘Sustainability’ by Toby Hemenway.
Titled ‘How Permaculture Can Save Humanity and the Earth, but Not Civilization‘:
And if all that isn’t enough here is the cherry on top:
What Permaculture isn’t – and is. by Toby Hemenway