Obviousness refers to an "obvious" method or process that lacks an inventive step,  a general patentability requirement present in most patent laws, according to which an invention should be sufficiently inventive — i.e., non-obvious — in order to be patented. The UK and under the European Patent Convention (EPC), while the expression "non-obviousness" is predominantly used in US patent law.

http://en.wikipedia.org/wiki/Inventive_step_and_non-obviousness