Definition of “improvement” - Learner’s Dictionary

improvement

noun [ C, U ] uk us /ɪmˈpruːvmənt/

B1 If there is an improvement in something, it gets better:

home improvements
There's been a noticeable improvement in her work this year.
He's a definite improvement on her last boyfriend.
Sadly, her health has shown no improvement.

(Definition of “improvement” from the Cambridge Learner's Dictionary © Cambridge University Press)