To make quiet or put at rest; to pacify or appease; to quell; to calm.
to allay popular excitement
To alleviate; to abate; to mitigate.
to allay the severity of affliction or the bitterness of adversity
To subside, abate, become peaceful.
To mix (metals); to mix with a baser metal; to alloy; to deteriorate.
(by extension) To make worse by the introduction of inferior elements.