boycott

from The American Heritage® Dictionary of the English Language, 5th Edition.

• transitive verb To abstain from or act together in abstaining from using, buying, dealing with, or participating in as an expression of protest or disfavor or as a means of coercion.
• noun The act or an instance of boycotting.

from The Century Dictionary.

• To combine in refusing to work for, buy from, sell to, give assistance to, or have any kind of dealings with, and
• in preventing others from working for, buying from, selling to, assisting, or having any kind of dealings with (a person or company), on account of political or other differences, or of disagreements in business matters, as a means of inflicting punishment, or of coercing or intimidating.
• noun An organized attempt to coerce a person or party into compliance with some demand, by combining to abstain, and compel others to abstain, from having any business or social relations with him or it; an organized persecution of a person or company, as a means of coercion or intimidation, or of retaliation for some act, or refusal to act in a particular way.

from the GNU version of the Collaborative International Dictionary of English.

• noun The process, fact, or pressure of boycotting; a combining to withhold or prevent dealing or social intercourse with a tradesman, employer, etc.; social and business interdiction for the purpose of coercion.
• transitive verb To combine against (a landlord, tradesman, employer, or other person), to withhold social or business relations from him, and to deter others from holding such relations; to subject to a boycott.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To abstain, either as an individual or group, from using, buying, or dealing with someone or some organization as an expression of protest.
• noun The act of boycotting

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a group's refusal to have commercial dealings with some organization in protest against its policies
• verb refuse to sponsor; refuse to do business with