Childlike and childish 天真和幼稚

I had been to America for only a few years, as I did not understand the actual meanings of the two words "childlike" and "childish". A minor misunderstanding was the result, and I nearly offended my supervising professor.

One day I had a chat with some professors and postgraduates in the office. the subject came to the character of my supervisor. She was a senior professor who was always very cheerful and enthusiastic, interesting and full of childlike innocence. I said without thinking, "She is childish." Actually what I meant to say is, "She is childlike."

Not long after that, my professor was told that I had said she was childish. She was a little unhappy to hear that, and asked me, "Did you say that I am childish?" I felt at once that something bad would happen to me. I hurriedly explained what I meant, and she forgave my inappropriately using the word.

"Childlike" and "Childish" are different, in that the former is a commendatory （褒义的）term, which praises one who is innocent and has characteristics of a child, while the latter a derogatory (贬义的）term, which describes an adult behaving like a child.