A reduction; a lessening; the sum abated.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
A decrease; a lessening; a deduction.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)
The act of abating; sum deducted from an account. A mark of dishonour in a coat of arms. Overthrow or defeat, as of a writ.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
The act of abating: the sum or quantity abated: ( her.) a mark of dishonor on a coat- of- arms.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)

Usage examples:

He saw it reach to the foot of the mountain, and at length it came up to the foot of the tree, but there was no abatement
- The Myth of Hiawatha, and Other Oral Legends, Mythologic and Allegoric, of the North American Indians by Henry R. Schoolcraft
He demanded some abatement he having agreed with my father for Barton's house, at a price which I told him I could not meddle with, but that as for anything to secure his title to them I was ready, and so we parted.
- Diary of Samuel Pepys, Complete Transcribed From The Shorthand Manuscript In The Pepysian Library Magdalene College Cambridge By The Rev. Mynors Bright by Samuel Pepys Commentator: Lord Braybrooke
Her grandmother did sufficiently awake to the danger of alarming the jealousy of Queen Elizabeth to submit to leave her in the ordinary chambers of the children of the house, and to exact no extraordinary marks of respect towards the unconscious infant; but there was no abatement in the Countess's firm belief that an English- born, English- bred child, would have more right to the crown than any " foreign princes," as she contemptuously termed the Scottish Queen and her son.
- Unknown to History A Story of the Captivity of Mary of Scotland by Charlotte M. Yonge