The Collaborative International Dictionary of English v.0.48:

bioengineering \bi`o*en*gin*eer"ing\ n.
   1. biological science applied to the study the relation
      between workers and their environments.

   Syn: ergonomics.
        [WordNet 1.5]

   2. the application of engineeering principles to solve
      problems in medicine, such as the design of artificial
      limbs or organs; -- called also biomedical engineering.
      [PJC]

   3. the branch of engineering dealing with the application of
      biological processes to the solution of practical
      problems, such as the manufacture of products by
      fermentation, the production and use of enzymes for
      various purposes, the use of microorganisms in
      environmental cleanup, etc.; -- called also
      biotechnology.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

biomedical engineering \bi"o*med`i*cal en`gin*eer"ing\ n.
   The application of engineeering principles to solve problems
   in medicine, such as the design of artificial limbs or
   organs; -- called also bioengineering.
   [PJC]

WordNet (r) 3.0 (2006):

bioengineering
    n 1: the branch of engineering science in which biological
         science is used to study the relation between workers and
         their environments [syn: biotechnology, bioengineering,
         ergonomics]