ill will is a noun meaning "the feeling of a hostile person". It carries 2 recorded senses.
the feeling of a hostile person
“he could no longer contain his hostility”
a hostile (very unfriendly) disposition
“he could not conceal his hostility”
Definitions, synonyms and semantic relations for ill will come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.