IPA: /əˈbeɪtə/
KK: /əˈbeɪtər/
A person or thing that reduces or lessens something, often in terms of intensity or amount.
The abater of the noise ensured a peaceful environment for everyone.
Abater is derived from the Old French word 'abattre', meaning to beat down or reduce. The prefix 'a-' (meaning to) combined with 'battre' (meaning to beat) indicates the action of causing something to lessen or diminish.
Think of 'beating down' something to make it less — that's what abater means.