\Sweet"en\, v. t. [imp. & p. p. {Sweetened}; p. pr. &
vb. n. {Sweetening}.] [See {Sweet}, a.]
1. To make sweet to the taste; as, to sweeten tea.
2. To make pleasing or grateful to the mind or feelings; as,
   to sweeten life; to sweeten friendship.
3. To make mild or kind; to soften; as, to sweeten the
   temper.
4. To make less painful or laborious; to relieve; as, to
   sweeten the cares of life. --Dryden.
         And sweeten every secret tear.        --Keble.
5. To soften to the eye; to make delicate.
         Correggio has made his memory immortal by the
         strength he has given to his figures, and by
         sweetening his lights and shadows, and melting them
         into each other.                      --Dryden.
6. To make pure and salubrious by destroying noxious matter;
   as, to sweeten rooms or apartments that have been
   infected; to sweeten the air.
7. To make warm and fertile; -- opposed to sour; as, to dry
   and sweeten soils.
8. To restore to purity; to free from taint; as, to sweeten
   water, butter, or meat.

\Sweet"en\, v. i.
To become sweet. --Bacon.