Wiktionary
almost all
det. 1 (&oth almost all English) 2 (context mathematics English) (l en All, except for a negligible set, i.e. finite, countable or of zero measure.)
Wikipedia
Almost all
In mathematics, the phrase "almost all" has a number of specialised uses which extend its intuitive meaning.
Usage examples of "almost all".
To the right was good he could see almost all the way up to the corner, although Bear Street itself was lost in a haze of rain.
Water spouts up from what's left, at first almost all the way to the ceiling.
Then she realized that almost all the computer systems had been turned off.