There are hundreds of definitions, but we could define Biomimesis as the study of the structure and function of biological systems as models for the design and engineering of materials and machines. (Wikipedia) or as the attempt to learn from nature; it deals with the development of innovations on the basis of investigation of natural, evolutionarily optimized biological structures, functions, processes, and systems. (Potencials and Trends in Biomimetics; A. Gleich, C. Pade, U. Petschow, E. Pissarkoi)

At least we recognize these three views:

 Nature as a model: is the imitation of models, systems and elements of Nature for the purpose of solving complex human problems.
► Nature as measure: Biomimetics (known as Biomimicry in USA) uses an ecological standard to judge the correctness of our innovations. After billions of years of evolution, Nature has learned what works, what is appropriate and what endures.
► Nature as mentor: makes Biomimetics as a new way to watch and assess Nature. A new era, based not on what we can extract from the natural world, but what it can.