day-by-day

[dey-bahy-dey] /ˈdeɪ baɪˈdeɪ/
adjective
1.
taking place each day; daily:
a day-by-day account.
Origin
1350-1400; Middle English
Idioms and Phrases with day by day

day by day

On each successive day, daily, as in Day by day he's getting better. Percy Bysshe Shelley used this expression, first recorded in 1362, in Adonais (1821): “fear and grief ... consume us day by day.”