The Institute of Electrical and Electronics Engineers’ (IEEE) Computer Society has produced and maintains a document called “SWEBOK, Guide to the Software Engineering Body of Knowledge.” 

SWEBOK provides topical access to the published literature on software engineering. It is a resource with immense value.

SWEBOK begins with this definition of Software Engineering:  "the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software:  that is, the application of engineering to software."  (SWEBOK, “Introduction to the Guide” page xxxi)

The most recent version of this document was approved in November 2013. You can find it here: