The full definition is:
Dormant Specification (Dormant): A Specification that does not have an identified Specification Lead or Maintenance Lead. All Specifications become Dormant at the end of their life cycles.
I agree that the second sentence is problematic. I know what it's trying to say - "all specs become Dormant when they become dormant" but that doesn't help much.
We could just delete that sentence, but I'm not sure about the first one either. The intent of the second sentence is to suggest that there's a point at which all specs naturally reach a stable state (when no further work will be carried out on them.) However, this isn't captured in the first sentence. There may well be an identified ML. In fact there always is (the last Spec Lead) unless something has been brought to our attention. This doesn't mean that that person is actively maintaining, or ever will maintain the spec.
What this should really say is something like "a spec that is not being actively developed." This would bring it more into line with the only usage of the term in the document, in section 5.1.1 RELINQUISHING OWNERSHIP, where we say "If no replacement can be found, or if the Transfer Ballot fails, then the PMO will declare the Specification to be Dormant and no further maintenance can be carried out."
I'm going to rename this issue to "The definition of Dormant needs clarification."