Lessen
Part of speech: verb
Definition: To make less; to diminish; to reduce. To become less.
Subside
Part of speech: verb
Definition: To sink or fall to the bottom; to settle, as lees.To tend downward; to become lower; to descend; to sink.To fall into a state of quiet; to cease to rage; to be [calmed]; to settle down; to become tranquil; to abate.