For me medias has always been generically any type of socks (when speaking to my mom from South America). I'm normally seeing 'stockings' as the correct translation, which in American English would be either a very old fashioned or long pair of socks, or a very sexy or old fashioned substitute for pantyhose. (They are not attached together, and also not the same as tights.) Stockings and socks are not really interchangeable in American English. But I am also getting socks as a correct answer. I am totally fascinated by all of the socks words you are all mentioning from all over the world.
Medias, as far as I know can be used in South America as "socks", whilst is stockings in Europe. It means also "long socks", such as the ones used in football.
The reason is that in the old times there was only a type, which was medias on the bottom of the leg and calzas on the upper. The evolution of clothes resulted in kind of a mess really. If you are aware of what calzas and medias (old time) are, all derivations of those will be more or less clear to you
then why when I encountered largo for the first time did it give three meanings - the first two of which were long and large ( I wrote them down on my vocab book) - obviously I try to use the feeling of the word that fits the language being translated into and generally stockings come in large not long
Like I said, this is to the best of my knowledge. I have never encountered a case where it was actually acceptable to translate largo as large.
Duolingo is not always 100% accurate in their dictionary. It's best to check an actual Spanish/English dictionary.
And "Your stockings are long," sounds commentary.
Where I come from, "Your stockings are large," would be considered insulting.