Question: I was able to read about cyber-warfare and how the United States regularly uses the term. However, the term is said to [still be ambiguous](https://en.wikipedia.org/wiki/Cyberwarfare#Definition) with the former Cyber Security Coordinator for the Obama Administration saying that

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> "there is no cyberwar... I think that is a terrible metaphor and I think that is a terrible concept. There are no winners in that environment."
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What I want to know is, does any department of the United States government have a definition for cyber-warfare that members of that department consider to be 'official'?

Answer: 
There [seems to be no formal definition](https://fas.org/sgp/crs/natsec/R43955.pdf) (as of 2015):

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> Although there is no clear doctrinal definition of “cyberwarfare,” it is typically conceptualized as state-on-state action equivalent to an armed attack or use of force in cyberspace that may trigger a military response with a proportional kinetic use of force. 
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[US Legal](https://definitions.uslegal.com/c/cyber-warfare/) gives this definition:

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> Cyber warfare refers to a massively coordinated digital assault on a government by another, or by large groups of citizens. It is the action by a nation-state to penetrate another nation's computers or networks for the purposes of causing damage or disruption. The term cyber warfare may also be used to describe attacks between corporations, from terrorist organizations, or simply attacks by individuals called hackers, who are perceived as being warlike in their intent.
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However, it is unclear whether this is an official definition used by the US government or is something they defined themselves, as it doesn't cite any US codes.
While not an official definition of *cyberwar*, the Congressional Research Service has published studies including this term. That research breaks it down to more precise terminology used by the U.S. military. For example, see [Information Operations, Electronic Warfare, and Cyberwar: Capabilities and Related Policy Issues](https://fas.org/sgp/crs/natsec/RL31787.pdf). 

The broadest preferred term, close to cyberwar, would be **Information Operations**, which can be broken down into:

* Psychological Operations,
* Military Deception,
* Operational Security,
* Computer Network Operations, and
* Electronic Warfare

Using a term including "war" seems an attempt to put in place some artificial threshold of how much is too much. It seems unlikely there will ever be a declared cyber-war because the effects of all of these operations would be diminished by openly stating they are underway.