DDoS (Distributed DoS) is characterised by floods creating a DoS (in all available definitions). A single node causing a flood successfully is kind of rare.

But DoS can be caused by a broad range of triggers. 

[CVSS even has an example of a software crash classified as DoS for you:][1]

> Due to a flaw in the handler function for RPC commands, it is possible
> to manipulate data pointers within the Virtual Machine Executable
> (VMX) process. This vulnerability may allow a user in a Guest Virtual
> Machine to **crash** the VMX process resulting in a **Denial of Service**
> (DoS) on the host or potentially execute code on the host.
[empasis mine]

[And from Wiki][2]:

> Denial-of-service attacks are characterized by an explicit attempt by
> attackers to prevent legitimate use of a service. There are two
> general forms of DoS attacks: **those that crash services** and those that
> flood services. The most serious attacks are distributed.

So, yes, a simple crash is a DoS. 


 [1]: https://www.first.org/cvss/examples
 [2]: https://en.wikipedia.org/wiki/Denial-of-service_attack