To reduce in amount, degree, or intensity; lessen: a program to abate air pollution. Law To put an end to: The court ordered that the nuisance of the wrecked vehicle in the front yard be abated. To make void: The judge abated the lawsuit. To reduce for some period of time: The town abated the taxes on buildings of historical importance for three years. To fall off in degree or intensity; subside: waiting for the rain to abate. See Synonyms at decrease. Law To become void. To become reduced for a period of time.