Indoctrinate means "brainwash" to many people, but its meaning isn't always so negative. When the verb first appeared in English in the 17th century, it simply meant "to teach"—a meaning linked closely to its source, the Latin verb docēre, which also means "to teach." (Other offspring of docēre include docile, doctor, document, and, of course, doctrine). By the 19th century, indoctrinate was being used in the sense of teaching someone to fully accept only the ideas, opinions, and beliefs of a particular group.