not less than a certain amount or number
You need to drink at least eight glasses of water every day.
used to indicate that something is the minimum that should be done
At least try to finish your homework before going out.
used to highlight a positive aspect in a generally negative situation
The hotel was far from the beach, but at least the rooms were clean.
used to soften a statement or make it less definite
I think I've solved the problem, at least, that's what I hope.