lessen

UK: /ˈlɛs^ən/ US: /ˈlɛsən/ ,(les′ən)

WordReference Random House Learner's Dictionary of American English © 2025

less•en /ˈlɛsən/   v. 

1. to (cause to) become less;
   reduce: [no object]
   His shyness lessened as he grew older.
   [~ + object]
   Cold lessens feeling.

WordReference Random House Unabridged Dictionary of American English © 2025

less•en  (les′ən), v.i. 

1. to become less.

v.t. 

2. to make less;
   reduce.
3. [Archaic.] to represent as less;
   depreciate;
   disparage.

• 1300–50; late Middle English lessenen, lasnen (see less, -en¹); replacing Middle English lessen

Collins Concise English Dictionary © HarperCollins Publishers::

lessen / ˈlɛs^ən/ verb

1. to make or become less
2. (transitive) to make little of