$*

• The stem with which an implicit rule matches. If the target is 'dir/a.foo.b' and the target pattern is 'a.%.b' then the stem is 'dir/foo'. The stem is useful for constructing names of related files.

$@

• The file name of the target of the rule.

$<

• The name of the first dependency.

$?

• The names of all the dependencies that are newer than the target, with spaces between them.

$^

• The names of all the dependencies, with spaces between them.