To prevent or discourage from acting, as by means of fear or doubt: "Does negotiated disarmament deter war?” ( Edward Teller). See Synonyms at dissuade.
To prevent or discourage the occurrence of an action, as by means of fear or doubt: "It's this edge that gives nuclear weapons their power to deter” ( Thomas Powers).
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.