What could be a valid definition of DevOps to introduce it to a novice?
DevOps in a nutshell

From Wikipedia:


  DevOps (a clipped compound of "software DEVelopment" and "information technology OPerationS") is a term used to refer to a set of practices that emphasize the collaboration and communication of both software developers and information technology (IT) professionals while automating the process of software delivery and infrastructure changes.
  
  It aims at establishing a culture and environment where building, testing, and releasing software can happen rapidly, frequently, and more reliably.


From Overview:


  
  
  Venn diagram showing DevOps as the intersection of development
  (software engineering), operations and quality assurance
  (QA)


While there is no single "tool" for DevOps, but rather a set of tools, also known as a DevOps toolchain:


  
  
  Illustration showing stages in a DevOps toolchain


Illustrations of DevOps

Below are a few quotes from some of the questions on DevOps.SE, which all seem to somehow fit / confirm part of the DevOps description above:


From 'What is the difference between SRE and DevOps?':


  ... DevOps is about maintaining code ...

From (an answer to) 'How do I hire a good DevOps, fitting my company?':


  ... It is a common misbelief that “DevOps” is a role in a company. The word merely denotes an organisational shift in software companies ...

From 'Does my organization need adopt Agile Soft. Dev. before adopting DevOps?':


  ... there are still organisations which are not practicing Agile in their software development, who might be interested in adopting DevOps ...



DevOps is NOT a role

Below are a few quotes from some of the questions on DevOps.SE, which all seem to illustrate that DevOps is NOT a role:


From (an answer to) 'What is the difference between Sysadmin and DevOps Engineer?':


  ... DevOps is not a role (when used as such it's more a buzzword than a real role).

From (an answer to) 'How do I hire a good DevOps, fitting my company?':


  ... It is a common misbelief that “DevOps” is a role in a company. The word merely denotes an organisational shift in software companies ...