Sweeten means to make something taste sweeter or to add sweetness to it.
When we talk about sweetening food or drinks, we usually mean adding sugar or honey to make them more pleasant to eat or drink. But the word "sweeten" can also be used in other ways, like when you're sweetening someone's mood by doing something nice for them, or even when a difficult situation becomes easier or less stressful over time. For example, "The news was hard to hear at first, but it will begin to sweeten once we get used to the idea."
How common is "sweeten"?
Word sweeten is considered rare in modern English. It appears most frequently in magazine texts and less often in other writings.
Definitions
verb
(transitive) To make sweet to the taste.
Example: to sweeten tea
(transitive) To make (more) pleasant or to the mind or feelings.
Example: to sweeten life
(transitive) To make mild or kind; to soften.
Example: to sweeten the temper
(transitive) To make less painful or laborious; to relieve.
Example: to sweeten the cares of life
(transitive) To soften to the eye; to make delicate.
(transitive) To make pure and healthful by destroying noxious matter.
Example: to sweeten rooms or apartments that have been infected
(transitive) To make warm and fertile.
Example: to dry and sweeten soils
(agriculture, transitive) To raise the pH of (a soil) by adding alkali.
(transitive) To restore to purity; to free from taint.
Example: to sweeten water, butter, or meat
(transitive) To make more attractive; said of offers in negotiations.
Example: to sweeten the deal by increasing the price offered
(intransitive) To become sweet.
(music, transitive) To supplement (a composition) with additional instruments, especially strings.