1 [uncountable and countable]
the act of improving something or the state of being improved
There's been a big improvement in the children's behaviour.
an improvement on earlier models
We need to carry out some improvements to the system.
dramatic/major/significant/substantial etc improvement
a marked improvement in her condition
It could be quite some time before we see any improvement.
This month's sales figures show some improvement.
Your English is much better, but there's still room for improvement (=it could be even better).
a change or addition that improves something:
Are you making some improvements to your home?