Understanding stamp collecting terms is very important. Philatelic terms and abbreviations can be very confusing to the novice collector, and when either buying or selling stamps, not knowing exactly what they mean can be very risky!
In this day of Worldwide commerce, on the Internet, it might be necessary to have an understanding of collecting terminology, not only in English, but in various other languages, as well.
Let's look at some examples from US, UK, and German eBay lot descriptions.
US #527 2c Plate Block of 6 VF MLH
US = United States
#527 = (Scott Catalog) #527
2c = Denomination
Plate Block of 6 = Description
VF = Very Fine Centering
MLH = Mint Lightly Hinged
1992/5 £1 CASTLE INTERPANNEAU BLOCK UMM
1992/5 = Issue of 1992-1995
£1 = Denomination
CASTLE = Description
INTERPANNEAU BLOCK = Cross Gutter Block
UMM = Unmounted Mint = Mint Never Hinged
DR Adler Brustschild Mi Nr 9 / 1872 gest
DR = Deutsches Reich = Name of the Country
Adler Brustschild = Eagle with Shield = Description
Mi Nr 9 = Michel Catalog #9
1872 = Issue of 1872
gest = gestempelt = Used
Foreign sellers often describe their lots using the YEAR the stamp was issued. This is a great help when searching the online auction houses, without having to know the catalog numbers of all the different stamp catalogs being used by the foreign sellers. When I'm searching Delcampe or any of the foreign eBay sites, I always use the year of the issues in my searches, as searching for catalog numbers will only give you hits on the particular sellers that are using those numbers in their lot descriptions.
Many foreign sellers, in order to appeal to a multinational market, use only the YEAR and name of the stamp to describe their stamp lots, instead of using any catalog number references. Even for an American seller, selling on an American site, it would be wise to use the YEAR in the description, so foreign visitors to the site will be able to locate and understand what they are selling, based on the lot description.
For those that may wish to sell a stamp lot in an online auction, one very important thing is to MAKE SURE YOU SPELL THE COUNTRY NAME AND DESCRIPTION PROPERLY. If the country name or the description is wrong, it may cause people searching for particular lots NOT TO FIND your lot. That could result in your lot not selling or maybe selling for the minimum bid, because few people ever saw your lot. The other day, I was looking at a blog posting, where someone was selling a "collection of stumps" -- this might cause come collectors to chuckle, but no one is probably going to take this particular posting very seriously.
There is no need for me to recreate-the-World here, as far as dictionary listings and abbreviations of philatelic terms, because there are already many excellent philatelic terminology sites on the Internet. I have provided links, that you can click on, to some of the better ones.
major stamp catalogs have introductions, featuring illustrated philatelic information and stamp
collecting terms and abbreviations, that you can use as well.