In one sentence
Cooperative writing is writing-with-AI in which the human remains author, editor, judge, and accountable party, while the model serves as collaborator, drafting instrument, critic, or accelerator.
The term matters because the public argument about AI writing often collapses several different practices into one accusation. A student submitting an untouched model answer, a marketing department flooding the web with anonymous filler, a novelist using a model to test a plot problem, and a professor asking an agent to draft the first version of a definition are not the same act.
Cooperative writing names the disciplined version. The human supplies intention, taste, domain knowledge, responsibility, and final judgment. The model supplies speed, alternative phrasing, associative reach, and sometimes useful resistance. The output is neither pure human performance nor anonymous machine sludge. It is a supervised artifact.
This Dictionary is itself an experiment in cooperative writing. The operator names terms, sets the voice, corrects the frame, approves publication, and remains accountable. The agent drafts, remembers, cross-links, checks, and sometimes says when a claim is too large. The result is not pretending to be unassisted human prose. It is bylined, voiced, source-backed writing produced in the open under human judgment.
The moral distinction is not whether AI touched the prose. The moral distinction is whether anyone is answerable for it.