1. a smoked herring.
2. something intended to divert attention from the real problem or matter at hand; a misleading clue.
3. Also called red-herring prospectus. Finance. a tentative prospectus circulated by the underwriters of a new issue of stocks or bonds that is pending approval by the U.S. Securities and Exchange Commission: so called because the front cover of such a prospectus must carry a special notice printed in red.
4. any similar tentative financial prospectus, as one concerning a pending or proposed sale of cooperative or condominium apartments.
1375–1425; late ME