to teach a biased or partisan principle, perspective, or opinion, and/or to convince a person or group to accept views or beliefs unquestioningly/uncritically;
e.g. Many totalitarian leaders aim to indoctrinate the youth of the nation to serve them with fierce loyalty.
(verb)
in old usage, to offer someone teaching or instruction on the basics or fundamentals of something;
e.g. He took it upon himself to indoctrinate them with some facts about birds.