These words mean "to teach," but to teach by repeated statements, by direct advice, by pointed suggestion: "By lecturing earnestly and persistently, the professor inculcated is his students a love for good literature. He indoctrinated them with the underlying theories of creative imagination." The Latin word from which inculcate is derived means "stamped" or "trodden," thus emphasizing the idea of forceful instruction. Indoctrinate suggests doctrine, so that the word is usually applied to teaching that involves principles and ideas, especially religious or moral doctrines and beliefs.
Dictionary of problem words and expressions. Harry Shaw. 1975.