Meaning of “gradually” - Learner’s Dictionary

gradually

adverb us uk /ˈɡrædʒuəli/
The voices gradually became louder.Sales have gradually declined.The pain of parting gradually lessened over the years.The change came gradually.Gradually, she began to feel better.

B2 slowly over a period of time:

Gradually he began to get better.

(Definition of “gradually” from the Cambridge Learner’s Dictionary © Cambridge University Press)