the GNU version of the Collaborative International Dictionary of English
n. The state or habit of not intervening or interfering.
The Century Dictionary and Cyclopedia
n. The act or policy of not intervening or not interfering; specifically, systematic non-interference by a nation in the affairs of other nations, or in the affairs of its own states, territories, or other parts.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a foreign policy of staying out of other countries' disputes
Word Usage
"US "nonintervention" appears to be a highly flexible concept."