"Gradual change" refers to a slow and steady transformation or development over time. Instead of happening suddenly or abruptly, it occurs gradually, with small and incremental shifts or improvements. Full definition
The researchers documented long stretches of gradual change in all three species, with different features changing at different times. (scientificamerican.com)
Many experts recommend making gradual changes in the diet. (wellnessevidence.com)
For me, faith has never been a matter of conversion; it's been a matter of evolution, of gradual change over time. (rachelheldevans.com)