You're likely to see quite a lot of jargon specific to the collector community on this blog, and I don't want to have to explain things every time I use a term or initialism, so here is a glossary as a quick reference for the layman or beginning collector!
If there's a term I've used (or that you've seen elsewhere) and you don't see it in this glossary, feel free to email me or send an Ask to my tumblr!
Age Spots - Refers to a condition which results in spots on a (usually G1) pony; it is believed to be a result of vinyl deterioration, and while there is no "cure," it cannot spread to other ponies in your collection. **also known as cancer/pony cancer or VDS/vinyl deterioration spots
Alternate Rehair - A form of customization where the customizer changes nothing about the pony except for the color (and sometimes material) of its mane and/or tail.
Argie - Refers to a Nirvana pony made in Argentina.
BAB/BABW - Refers to MLP plush dolls produced by Build-A-Bear Workshop.
Backcard/Backcard Story - Ponies come packaged either in a plastic bubble on a card or inside a box; the cards are known as "backcards," and even a loose backcard on its own can carry some collector value (although not everyone collects backcards, and different ponies' cards can vary in collector value). The back of a pony's card also featured a little story about the pony; this is the "backcard story."
Bait/Baity - A pony who is in very poor condition (read: beyond restoration) is often referred to as being "baity." That is, potential bait for a customizer to create a new pony from one which is, for all intents and purposes, already ruined and has no more real collector value on its own.
BB/Blind Bag - A miniature pony figure exclusive to G4; these small figures feature a molded mane and tail, and come sealed in individual bags. The marketing idea is that you don't know which figure you are getting (hence "blind" bag), but each character has its own individual code printed on the bag, so a savvy collector doesn't run the risk of purchasing accidental doubles. **"BB" can sometimes also refer to G1 adult ponies in the Big Brother mold; I don't really use this initialism for them, though.
BBE - Beddy-Bye-Eyes; refers to the Beddy-Bye-Eyes baby ponies.
BMBB - Refers to the Brush Me Beautiful Boutique playset, released in Year 6 of G1 production.
BnG - Refers to the Brush 'n Grow Ponies, released in Year 6 of G1 production.
Brushable - The "classic" style of My Little Pony, featuring a mane and tail which can be brushed and styled.
Buddy L/Buddy L Corp - Refers specifically to a line of fakie ponies produced by the Buddy L Corp toy company; these were called "Talk To Me Pony" and made horse noises when you squeezed their flanks.
Bushwoolies - Bushwoolies are little furry creatures that first showed up in the My Little Pony 'n Friends special, Escape from Catrina. Bushwoolies are also featured as companions to the first run of Princess ponies, in Year 5 of G1 production.
Cancer/Pony Cancer - Refers to a condition which results in spots on a (usually G1) pony; it is believed to be a result of vinyl deterioration, and while there is no "cure," it cannot spread to other ponies in your collection. **also known as age spots or VDS/vinyl deterioration spots
CF - Concave Feet; the second release of the original six ponies, as well as some versions of Peachy, were produced with hooves that are concave on the bottom. This is standard for all other ponies.
Chase/Chase Variant - This is a special variant of a figure which is usually produced in limited quantities, with the intention that collectors will want to "chase" it down to add to their collections.
CMM - Cutie Mark Magic; refers to the Cutie Mark Magic line of G4 ponies. These ponies feature their cutie marks in repeating patterns and/or unusual places on their bodies.
Collector Pose (CP) - This is the G1 pony mold that the original six ponies were released in; it is the same pose as My Pretty Pony, which is the forerunner of the MLP franchise.
Core 7 - The seven main characters of G3 production: Cheerilee, Pinkie Pie, Rainbow Dash, Scootaloo, Starsong, Sweetie Belle, and Toola-Roola.
Cutie Mark - In G3, the symbols printed on ponies' flanks were referred to as "cutie marks." The idea of cutie marks has been expanded upon as a major part of the world-building for G4.
Deboxing/Decarding - Refers to the act of removing a pony from its original packaging.
Deflocking - Refers to the process of removing the flocking from a So Soft Pony, in order to restore or customize it.
DG/DG Babies - Refers to fakie babies from Dollar General; they have a similar look to that of the G1 Newborn baby ponies.
Display Side/DS - A pony's "good side." When putting ponies on display, there will always be one side which is best to have facing out. This is usually determined either by which direction the pony seems to be facing or which side of her body her mane naturally falls. Later generations tend to feature a pony's cutie mark only on one side of her body, so this is also a good way to tell which is the display side.
DnP - Refers to the Dance 'n Prance Ponies, released in Year 7 of G1 production.
DnW - Refers to the Drink 'n Wet Baby Ponies, released in Year 8 of G1 production.
Dolly Mix - Dolly Mix is a type of British candy; in 2009 and 2010, a miniature pony with brushable mane and tail was included inside specially marked packages of the candy.
Dream Beauties - Marketed during Year 8 as "all grown up My Little Ponies," Dream Beauties still featured some of the iconic MLP characteristics, such as brightly colored bodies with symbols; however, their bodies were much more realistic, anatomically (they were not as stylized/cartoony as the classic MLP molds).
EqG - Equestria Girls; refers to the G4 spin-off which features humanoid versions of My Little Pony: Friendship is Magic characters.
Factory Curl - Refers to the original condition of a curly-haired pony's mane and/or tail.
Fairy Tails - During Year 5 of G1 production, Hasbro released a line of toy birds who were similar to My Little Pony, in that they were brightly colored with brushable plumes and tails, and they featured symbols on their chests.
Fakie - Fakies are pony toys produced by toy companies other than Hasbro; in some cases, they come very close to resembling true My Little Pony figures. Many people actively collect fakies.
Fashion Style/FS - Refers to a mid-sized release of a G4 pony; these are called "Fashion Style" ponies because they come with outfits and styling accessories.
FF - Flat Feet; refers to the first release of the original six ponies (and Peachy), whose molds had hooves which were flat on the bottom.
FiM - Friendship is Magic; refers to the animated and comic book series central to G4.
FT - First Tooth; refers to the line of baby ponies who feature a single painted tooth sticking out of their mouths.
Funko - Refers to MLP figures produced by the toy manufacturer Funko, such as large vinyls, Pop! figures, or Mystery Minis.
G1 - Refers to the first generation of My Little Pony; produced from 1982-1995.
G2 - Refers to the second generation of My Little Pony; produced from 1997-2003, although US production ended in 1998.
G3 - Refers to the third generation of My Little Pony; produced from 2003-2009. Some event-exclusive ponies were made in G3 molds after the end of market production, as collector editions.
G3.5 - Refers to the brief redesign of My Little Pony which was produced at the end of G3. It features the same core characters as G3, but the art style and molds are so different from G3 that it is considered to be its own thing.
G4 - Refers to the fourth generation of My Little Pony, which began in 2010 with the animated series My Little Pony: Friendship is Magic.
G4Zilla/Zilla - Refers to G4 brushables released in the large Styling Size.
Grail - Many (if not most, or all) collectors have a "grail" pony; different collectors can have different criteria for what they consider to be a grail, but for me it means a pony (or particular set of ponies) who is particularly hard to find and/or tends to be quite expensive. Generally, it takes a long time before a collector gets their hands on their grail. Some collectors break this down further, having what they consider to be "major" and "minor" grails.
HSH - Refers to the Home Sweet Home playset, released during Year 7 of G1 production.
HTF - Hard to Find; refers to a pony or variant who is difficult to find.
In the Wild - When someone finds a pony or some other MLP merchandise in person at a store, garage sale, flea market, etc., it is sometimes referred to as finding that pony "in the wild."
ISO - In Search Of; used to advertise that you are actively seeking a particular pony or item.
Lanard - Refers to a type of fakie produced by toy manufacturer Lanard. Lanard also produced a line of non-pony animals, Pet Zoo, which some people actively collect.
Little Pretty - Little Pretty Kitty and Little Pretty Puppy were produced by Mattel from 1989-1991, perhaps in response to the popularity of My Little Pony. They have a similar look as MLP.
Mane 6 - The six main characters of G4 production: Applejack, Fluttershy, Pinkie Pie, Rainbow Dash, Rarity, and Twilight Sparkle.
MB - Mountain Boys; refers to a set of adult male ponies produced during Year 6 of G1 production, exclusive to the UK.
MGR - Refers to the Merry-Go-Round Ponies, released during Year 7 of G1 production.
MH - Refers to Monster High.
MIB - Mint in Box; refers to a pony who has not been removed from its original packaging.
MM - Refers to the Magic Message Ponies, released during Year 6 of G1 production.
MO - Mail Order; refers to ponies who were available by mail order as a special offer.
MOC - Mint on Card; refers to a pony who has not been removed from its original packaging.
Mommy Charms/Mummy Charms - Miniature figures made from a hard plastic in a pony Charmkins mold, featuring a small ring to add the figure to jewelry.
My Little Bunny/My Little Kitty/My Little Puppy - Extensions of the My Little Pony line which were released during Year 9 of G1 production. They were introduced as friends of the ponies.
My Pretty Mermaid - Mermaid dolls released by Hasbro's Playskool division in 1991. Similar to MLP, they featured bright colors and symbols on their tail fins.
My Pretty Pony - The precursor to the My Little Pony franchise, produced by Hasbro's Romper Room division in 1981.
Nirvana - Ponies who were licensed by Hasbro for production and release in select countries outside the US and UK. They often look much different from their original counterparts and come in many variants depending on their country of origin.
NSS - Non-So Soft; refers to a pony who has no flocking, but also has a So Soft counterpart.
PACS - Play and Care Sets; refers to G1 baby pony playsets. These included a baby pony, one large accessory (like a playpen or a rocker), and several small accessories (like a bottle, a diaper box, etc.).
PE - Refers to the Paradise Estate playset, released during Year 4 of G1 production.
Petites - Miniature pony figures made of a hard plastic, many with molded manes and tails. These were released during Years 8 and 9 of G1 production.
Piggy - Refers to a particular mold/pose of some Spanish Nirvana ponies.
Plasticizer - An additive to the plastic used to make vintage ponies. You can tell when the plasticizer is breaking down, because your pony will feel tacky/sticky to touch. There is no known way to stop this, and once the breakdown is complete, the pony will be completely hardened and inflexible.
PRnS/Princess Rinse n Spit/RnS - Refers to a fakie that features an open mouth full of teeth.
Regrind - Refers to a condition in ponies where the colors used in that pony's vinyl separate over time, resulting in large spots of color.
Rehair - The replacement of a pony's mane and tail, for either restoration or customization.
Repinking - Many ponies who originally had bright (but light) pink hair have had their manes and tails fade to white over time; repinking is the process of restoring the pink color
SHS - Sweetheart Sister; refers to G1 ponies produced in the Sweetheart Sister mold.
Smooze - On toy ponies, this refers to a condition on the pony such as pindot mold or ingrained dirt.
Squeaky Butt - Refers to a Nirvana pony made in Venezuela, who featured a squeaker inside its body, at the tail hole.
SS - Refers to flocked ponies released in the So Soft line of G1 production.
Styling/Styling Size - Refers to the largest size brushable release in G3 and G4 production. G4 styling sized ponies are also known as G4Zillas/zillas.
Sunburn - Refers to a condition where the plastic of a pony's body has become so damaged by the sun as to have caused a change in the color.
Sunfading - A method of restoring ponies by placing the pony in sunlight to fade marks that cannot be removed by soap and water, Magic Eraser, or other surface cleaning methods.
Symbol - Refers to the symbols on the flanks of G1 and G2 ponies.
TAF - Twice As Fancy; refers to G1 ponies whose symbols cover both sides of their bodies as well as their backs.
Takara - Refers to the chibi-style poseable ponies produced by Japanese toy manufacturer Takara. These were licensed by Hasbro, but the Takara fakies are also sought after by collectors.
TE - Refers to the Twinkle-Eyed ponies released during Years 4 and 5 of G1 production.
Tokidoki/Tokidoki Unicorno - Refers to stylized unicorn figures produced by Tokidoki.
Totsy - Refers to a type of fakie produced by toy manufacturer Totsy.
TRU - Refers to Toys 'R' Us.
VDS - Vinyl Deterioration Spots; refers to a condition which results in spots on a (usually G1) pony; it is believed to be a result of vinyl deterioration, and while there is no "cure," it cannot spread to other ponies in your collection. **also known as age spots or cancer/pony cancer.
Vennie/Venny - Refers to a Nirvana pony made in Venezuela.
Wingers - Refers to Summer Wing or Windy Wing Ponies, released during Years 6 and 7 (respectively) of G1 production.
