Let him finish his sentence. I know it tedious,but it is a bit rude to rush him or finish for him.
Maybe he's mirroring what you're doing to him?
Don't get drawn into it if he doesn't understand that there are different words for things. Literally ignore his correction!
As for the getting upset about having to do it wear things... Pick your battles.
Is he refusing to wear a coat out in the rain? Let him get wet, and offer it to him a few minutes into the rain, if he says yes, give it without comment on if you were right. If he refuses, just remind him, if he gets cold/too wet you'll have to do X instead.
Or, if you have the option,let him choose a coat or an umbrella (or whatever is two sensible choices)
I save my "this has to happen" for when it really matters, definitely helps there to be less conflict. Giving them choices and freedom within boundaries is good way to get them to push against everything.
Again,look at this way. If your DH told you to wear a coat, because it's raining. But you think you'll be fine... How would you feel? Especially if he carried on going on about it?
Probably pissed off and push back and say "I'll be fine thanks" and would you then want him to be "ha ha told you so" when you do realise he was right and needed a coat? Or would you rather the jacket was subsequently worn without comment from him? Except maybe something like "I hope you're nice and warm now" or whatever.