If something lessens or you lessen it, it becomes smaller in size, amount, degree, or importance.
例句
He is used to a lot of attention from his wife, which will inevitably lessen when the baby is born...他習慣了妻子對他的百般關注，但孩子出生后這種關注就會不可避免地減少。Make sure that your immunisations are up to date to lessen the risk of serious illness.要確保接種最新的疫苗，以降低患上嚴重疾病的危險。
英英詞典釋義
Noun
1. a change downward;
"there was a decrease in his temperature as the fever subsided""there was a sharp drop-off in sales"