Oracle Glossary: ALL

The ALL comparison condition is used to compare a value to a list or
subquery. It must be preceded by =, !=, >, <, <=, >= and followed by a list
or subquery.
When the ALL condition is followed by a list, the optimizer expands
the initial condition to all elements of the list and strings them together
with AND operators, as shown below.
SELECT … fields …
FROM   … table …
WHERE  sal > ALL (2000, 3000, 4000);