In China, the term “waijiao” denotes “diplomatic relations” or “foreign teachers” . These are so closely related that it is very difficult for me not to get them mixed up. Chinese is very easy in one way, you don’t have so many sounds to learn. You just have to keep track of the tones . . . In this case: wai4jiao1 and wai4jiao4 (diplomatic relations and foreign teacher respectively).
Incidentally, if you are a student of the tones, you will note a difference between what was said, what was written, and what you will find in a Chinese/English dictionary. While Chinese seem to have no trouble understanding each other, they often disagree on tones and stroke order.