Implacable

закля́тый

zakljátyj

(not able to be placated or appeased)

непрекло́нный

nepreklónnyj

(adamant; immovable — see also adamant, immovable)

непримири́мый

neprimirímyj

(not able to be placated or appeased)

несдвига́емый

nesdvigájemyj

(adamant; immovable — see also adamant, immovable)

неумоли́мый

neumolímyj

(not able to be placated or appeased)

неумолимый

neumolimyj

(impossible to prevent or stop — see also inexorable, unstoppable)