Why is 'application' not working in a subroute in Ember?

I'm developing an Ember frontend which has to handle an 'application' resource. My router looks like this:

this.route('applications', function() {
   this.route('application', { path: ':application_id'}
   );
);

I get the following error:

Assertion Failed: 'application' cannot be used as a route name.

This seems to conflict with 'application' route of the Ember application.

Changing the route name from 'applications/application' to 'applications/app' works, but this is not very elegant.

Does anybody know if/why a subroute can never be '.../application/...'?

Thank you!