A gradual change is one that happens slowly over time.
When people talk about changes happening gradually, they usually mean that they're not sudden or shocking. For example, if your town gets new public transportation and it's a slow process to build the whole system, the change might be described as gradual because it doesn't happen overnight. You start seeing little improvements here and there, like one new bus route at a time, but it takes months or years for everything to be in place. This means people can get used to the changes gradually, rather than being overwhelmed by them all at once.
An antiphon or responsory after the epistle, in the Mass, which was sung on the steps, or while the deacon ascended the steps.
Proceeding or advancing by small, slow, regular steps or degrees
Example: a gradual increase of knowledge; a gradual decline
