abate·ment /ə-'bāt-mənt/ n
1: the act or process of abating or the state of being abated
challenged the abatement of her bequest
abatement of a private nuisance by self-help — W. L. Prosser and W. P. Keeton
2: an amount abated: deduction; esp: a deduction from the full amount of a tax
in abatement: subject to termination because of a formal or procedural defect
there shall be no reversal in the Supreme Court...for error in ruling upon matters in abatement — U.S. Code
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.