This article is the list of jargon word used in world of LEGO fans. It consist of terms and abbreviations, that, probably, you may see here on BPJournal or on other LEGO-themed resourses. This list is not intended to be exhaustive and will be complemented.

ABS – Acrylonitrile Butadiene Styrene, the type of plastic that LEGO bricks are made from.
Ambassador – The title given to fan liaisons who represent fan organizations within the LAN.
AFOL – Adult Fan of Lego.
AFFOL – Adult, Female Fan of LEGO.
AFOFL – Adult Fan of Fabuland Lego.
Baseplate – Baseplate are large flat plates which you can use as a starting base for Lego buildings. Unlike standard plates, you cannot attach anything to the underside of them.
Billund – Billund, Denmark. Headquarters and primary design center for The LEGO Group.
BL – Bricklink. BrickLink is a venue where individuals and businesses from all around the world can buy and sell new, used, and vintage LEGO through fixed price services.
BOLOCS – Built Of Lots Of Colours.
BP – Battle Pack. These are small sets with a few figs with accessories and sometimes a small extra model, much like the old People Packs. These first appeared in the Star Wars line but now other themes (such as castle) have them as well.
BURP – Big Ugly Rock Piece. Those large strange shaped pieces including piece 6082 and piece 6083.
Brick – A universal name for a LEGO piece, regardless of shape or color. Also: In LEGO element taxonomy, any roughly cubic LEGO piece which is 3 or more Plates tall. Also: In technical terms, used to refer a specific piece shape, regardless of color.
Brickset – Brickset.com, a LEGO set database which catalogs LEGO sets and their inventories.
CC – Classic-Castle.com. A LEGO castle fan site with an associated online community.
Cheese Slope – A LEGO element with a 33° slope, 1 stud by 1 stud wide and 2 plates high (or 2/3 of a brick). Part number 50746. Useful for adding fine detail to LEGO creations. Named because the yellow and orange pieces look like a wedge cheese.
CMF – Collectable Minifigures. A recently occurred abbreviation for the LEGO® Collectable Minifigures series.
Custom – A LEGO creation or individual element that uses non-LEGO parts or modified parts, including decals, paint, or accessories from third-party vendors like BrickArms, BrickForge, and Big Ben Bricks.
DBG – Dqrk Bluish Grey colour.
DUPLO – Double Sized Bricks. Large bricks intended for very young children
EB – Eurobricks forum.
ERLING – Part (4070 or 30069) designed by Erling Dideriksen in 1979 – also known as a headlight brick.
Flickr – A large photo hosting website frequently used by LEGO builders to share creations. Adding MOC photos to Flickr’s LEGO-related photo pools is a good way to show off creations to fellow fans.
GREEBLE (GREEBLIE, GREEB) – Groupings of mechanical-looking detail elements.
Illegal – LEGO building techniques that break the “rules” for connections between LEGO elements followed by official LEGO set designers — particularly connections that stress the LEGO elements.
Jumper – A 1×2-stud LEGO plate with only 1 stud in the center. Part number 15573
KFOL – Kid Fan Of Lego.
LAN – LEGO Ambassador Network. The LEGO Company’s official outreach program for adult fans. LEGO designates fan organizations as an RLUG or RLFM and grants an ambassadorship with access to the LAN. LEGO distributes support to fan organizations via the LAN.
LBG – Light Bluish Grey colour.
LDD – LEGO® Digital Design(er) The official virtual building program by LEGO®.
LDraw – Lego® Draw The basis software with a huge parts library needed for CAD programs like MLCad.
LUG – Lego Users Group. Initially used to describe a local or regional LEGO club that met and interacted primarily in an offline or “real world” context. The term LUG has been extended by fans to include virtual and even ephemeral groups of LEGO fans, such as Eurobricks and VirtuaLUG. Many LUGs now also have an online presence, further blurring the line between traditional LUGs and online LEGO fan communities.
LUGBULK – A LEGO program available to RLUGs and RLFM through which bulk quantities of elements may be purchased at discounted prices
LURP – Little Ugly Rock Piece.
MF – Minifig.
Microscale – A scale for building models in which a minifig would be too large to represent a person. Varies between anything smaller than minifig scale to a scale where a figure would not be visible to the naked eye.
Minifig – Short for Minifigure.
Minidoll – The thin, curved figures featured in LEGO Disney Princess, Elves, and Friends themes. First introduced in 2012, the design is a trademark of The LEGO Company.
MLCad – Mike’s LEGO Computer Aided Design. A virtual building program using the LDraw parts library.
MOC – My Own Creation.
MOD – The Modification of an official LEGO set.
NPU – Nice Part Use. An unexpected way to use a LEGO element in a model. Often overused in praising a LEGO creation.
PAB – Pick A Brick. A pick a brick consists of a wall of boxes full of various bricks in which you can choose whatever piece you want.
RB – Reddish Brown colour.
RC – Remote Controlled. Sets that feature remote control, for example 8369 Dirt Crusher RC and 8475 RC Race Buggy.
Plate – Any LEGO piece which is 1/3 the height of a Brick.
RLUG – Registered LEGO Users Group; a term used by The LEGO Company to denote a local, geographically oriented LUG that is officially recognized by LEGO via the LAN.
RLFM – Registered LUG Fan Media; a term used by The LEGO Company to denote an officially recognized online LUG, news site, forum, magazine, or other fan organization that is not an RLUG.
SAH (or S@H) – Shop At Home Lego’s online store.
SIGFIG – Short for Signature Minifig. The minifigure version of a LEGO fan that he or she uses in online communities as an avatar. Sigfigs may or may not resemble the person physically, as LEGO fans used to interacting with each other online often discover at LEGO conventions.
SNIR – Studs Not In a Row.
SNOT – Studs Not On Top A building technique where studs are, surprisingly, not always on top. This can be achieved with pieces designed for the purpose and have studs and/or anti-studs) on two or more faces, or by using pieces in a creative way. For example, most of the hinge pieces are good for SNOTting.
SW – Star Wars. A popular licensed theme by LEGO® Star Wars.
TBB – The Brothers Brick. LEGO blog featuring custom creations built by LEGO fans all over the world, plus LEGO news, LEGO set reviews, and more.
Tile – Any LEGO plate which is devoid of all or most studs, giving it a smooth upper surface.
TFOL – Teenage Fan Of Lego.
TLC – The Lego Company.
TLG – The Lego Group.
Travis Brick – A modified 1×1 brick with studs on 4 sides. Named for Travis Kunce, a deceased fan who was known for his enthusiasm for the piece. Part number 4733. A common piece used in SNOT building.
UCS – Ultimate Collector’s Series. UCS.
WIP – Work In Progress.