Modifies a noun

• foe: The representatives of two races, once implacable foes, have become allies, maybe friends.

• hostility: The implacable hostility of communism toward faith in God could be explained by its claims to a monopoly on world views.

• hatred: Like Saddam Hussein, some of today's tyrants are gripped by an implacable hatred of the United States of America.

• enemy: They have shown themselves to be an implacable enemy of the workers ' movement over many years.

• opponent: Stephen Gould certainly is an " implacable opponent of.

• opposition: The moderate opposition has been silenced more effectively than the more implacable opposition.