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Humor is often far more effective than shouting.
You need more effective communication within the organization.
The troops should be deployed where they will be most effective.
The new vaccine is highly effective against all strains of the disease.
This is a very effective way of controlling pests and weeds.
Government ministers reached a 30-month agreement, effective from July 1.
The U.S. military is in effective control of the entire region.
This is the American English definition of effective. View British English definition of effective.