"Origins of words" by Susie Dent, Countdown 08/12/17 (prefix ortho-)

I have a prefix, which sounds on the face of it very boring. And lexicographers love prefixes and knowing your prefixes allows you to open a whole new world of words and to realise where they came from, especially if you know your classics. This prefix is ortho-. And ortho- heads up a whole host, a family of modern English words. It means straight or perpendicular. It's Greek-based. Metaphorical, too, it can imply integrity, correctness or standard, in some way. And there are many, many medical, zoological, botanical terms, that have this at the beginning. So, Orthoptera is a family of insects including grasshoppers and locusts and various other insects that have stright wings. So, that ortho- means straight in there already. That one's a bit obscure, maybe. But there are so many other words including ortho-, which once you understand that straightness, they make absolute sense. So, orthodondist is somebody who will straighten your teeth, the -dontist part obviously meaning teeth. So, they are a tooth straighteher. An orthopaedist, on the other hand,  if you talk about orthopaedics, the person who deals with abnormalities in bones anf joints, especially in children, and the -paedist comes from the Greek for child but etymologically, they are really concerned with the straight development of children's bones, so, again, that idea of straightness. And orthodox, somebody who has an orthodox opinion conforms to the standard, if you like. They are perhaps more conventional in their beliefs and subscribe to a particularly standard  type of doctrine related to whatever it is, whether it's religion or a custom. So, orthodoxy, appearing in English in the 1500s, means literally a straight or correct opinion. So that ortho-, simply meaning straight, will give you a way into so many words that on the face of it look actually very difficult but they're not!