Almost all

In mathematics, the term "almost all" means "all but a negligible quantity". More precisely, if ${\displaystyle X}$ is a set, "almost all elements of ${\displaystyle X}$" means "all elements of ${\displaystyle X}$ but those in a negligible subset of ${\displaystyle X}$". The meaning of "negligible" depends on the mathematical context; for instance, it can mean finite, countable, or null.

In contrast, "almost no" means "a negligible quantity"; that is, "almost no elements of ${\displaystyle X}$" means "a negligible quantity of elements of ${\displaystyle X}$".