LEGO glossary

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Are we using weird acronyms and phrases? It happens a lot in the LEGO® fan world, so here is a definition of some of them. Some of these are explanations of nicknames from the community, some are the lesser-known names and nicknames from The LEGO Group itself... and some are quite simply just our own inventions! 

If you are confused by the dual names of colours: we generally use the name created by the fan community as used by the website BrickLink, but might also use the official name used by The LEGO Group. By the way, LEGO designers use neither of these! They use the Color ID number, which you can look up on this useful colours spreadsheet by Rylie Howerter.

And as for those confusing piece numbering systems I include - see Element ID and Design ID.

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AFOL

Adult Fan Of LEGO®. The standard acronym used by the community to describe themselves, used since the early days of online LEGO community began to form. This thread is purported to be its coining. (Thanks to DaveE for the great link. Plenty more on his amazing AFOL History Project.)
TFOLs (Teen Fans of LEGO) are another distinct group of people who fall outside The LEGO Group's main focus since probably most kids stop playing with LEGO in their teens. 

Apollo Stud

Tim accidentally christened the 1x1 round plate with hole (Design ID 85861) with this name after mishearing LEGO® designer Jamie Berard say "a hollow stud". Although he corrected the article, the nickname stuck and still gets used by many! This part is also known in the UK as the Polo, after the confectionery.

Bley

Bluish Grey, known as Stone Grey within TLG. In 2004, TLG changed the shades of light and dark grey to be a little bluish instead of greenish. They did it in all innocence never imagining anyone would care or even notice... but there was a massive outcry from the AFOL community. 'Bley' was a derogatory term the community coined and it stuck, though now used with more affection with the fullness of time.

CCBS

The Character and Creature Building System. A system for creating action figures which TLG formalised in 2011. The usual system for building with LEGO® elements involves studs and tubes, but at the heart of CCBS are the large Technic ball and C-cup connectors. One of its designers, Christoph Röttjer, explains it succinctly in his CCBS diagram and one of our regular contributors, Skye Barnick, goes into more detail about CCBS in this post about the return of LEGO® Bionicle.

Cheese

An easier name for this popular tiny slope than its official name, Roof Tile 1X1X2/3. I'll let you draw your own conclusions as to how it got this name.

Constraction

TLG's internal name for the building method used for buildable figure ranges such as LEGO® BIONICLE and LEGO® HERO Factory. See CCBS above.

Conversion set

The set that brought an adult out of their Dark Age, making them an AFOL.

Dalek

Part 4733, a SNOT brick that's like the regular 1X1 brick but with hollow studs on all four sides as well as the top . It is a greatly-loved part amongst AFOLs and has many nicknames; I think most the common one is the Travis brick but I prefer this British nickname given due to its vague resemblance to the Daleks, an alien from Doctor Who.

Dark Ages

The period between when you stopped building with LEGO® toys as a child and then started again.

Design ID

The LEGO Group assign a reference number to each different part. You can find them somewhere on the underside of most LEGO pieces (they started doing this around 1985). These are called the Design ID, but in the community they are usually just called the part number. You can use them to search on Brickset, Brick Owl, Rebrickable, BrickLink and the LEGO Pick A Brick and Replacement Parts sites.
See also Element ID below.

Element ID

As well as every part having a number, The LEGO Group also assign a reference number to each different element. An element is unique in colour as well as shape, so there are squintillions of elements! You can find them in every LEGO instruction manual (except old ones) at the end where the inventory is listed. These are called the Element ID. You can use them to search on Brickset, Brick Owl, Rebrickable, BrickLink and the LEGO Pick a Brick and Replacement Parts sites.
See also Design ID above.

Erling

Also known as the headlight brick or washing machine, this is one of the most beloved SNOT bricks around thanks to the many unusual aspects to its geometry and the anti-stud hole on its back side. It was designed in 1979 by a chap called Erling Dideriksen.

Greebles

Greebling is a term used primarily in the sci-fi movie industry to refer to the little bits of stuff applied to the exterior of a spaceship to make it look cool. The term can be used more widely than that though - Wikipedia defines it as "fine detailing added to the surface of a larger object that makes it appear more complex, and therefore more visually interesting" - but in the FOL world, spaceships are probably the most common type of MOC where greebles are used.

Illegal connections

One of the great joys of building with LEGO® elements is connecting the pieces in ways that set instructions wouldn't suggest. We've all stuck a plate between the studs of a brick, right? Actually, even LEGO designers used to do that one decades ago. But this is an example of what The LEGO Group unofficially term 'illegal connections', because it places stress on the elements (however minute) and/or is an unstable method of building. These connections are not entirely known outside of TLG but this (now old but still very relevant) presentation by Designer Jamie Berard explains many. Children, TFOLs and AFOLs alike are terribly disrespectful of such LEGO 'laws', as we are not a responsible toy company. As such we flagrantly enjoy disobeying them and even boast of illegal connections we've discovered. Then cry when we knock the model lightly and it shatters into a thousand elements.

Legal connections

See Illegal connections above.

LUG (and RLUG and RLFM and RLOC)

LEGO® User Group. Fan clubs around the globe are known as LUGs and the ones officially supported by The LEGO Group are RLUGs (Recognized LEGO User Groups). Fan organisations that are not clubs, like magazines and websites (such as New Elementary!) are called RLFM - Recognized LEGO Fan Media or RLOC - Recognized LEGO Online Communities. Each RLUG and RFLM has an Ambassador who communicates with the community engagement department of TLG. Find your nearest RLUG and other great resources on the LEGO Ambassador Network website.

LUGbulk

One of the remarkable things TLG do for fans is offer them bulk parts at a bargain price. This occurs annually through the LUGbulk programme, and you need to be a member of a LUG to participate. It's called bulk for a reason - elements must be ordered in batches of 50 minimum, and there is a hefty minimum spend required in order for a LUG to qualify. Also, it takes a really really long time to receive your parts because these requests need to be fulfilled when the factory is not madly busy making regular sets for sale. Nevertheless it's an amazing way for fans to be able to build huge models - in the long term!

Minifigures and Minifigure Scale

LEGO® Minifigures, abbreviated to 'minifigs' by the community, are he little LEGO people, introduced in 1978. Previously they had no posable arms or legs and no facial expressions, but that was soon changed to the bendy little folk we know and love today. Something built in 'minifigure scale' means all the buildings, cars etc are built at the same scale to a minifigure. The human-to-minifigure ratio is very vague due to the strange shape of minifigures, so two minifig scale models might not match. It is about 1:40 to 1:50.

MOC

My Own Creation. A model built by a fan. As with so many words in English the noun has transmogrified into a verb, so "MOCing" means building your own creation.

Modular Buildings

This is a series of sets from the LEGO® Icons (previously Creator Expert) theme aimed primarily at adult builders and collectors, each consisting of a large building with removable storeys. The buildings all connect to build a street in minifigure scale. One building has been released each year since 2007, when designer (and AFOL) Jamie Berard began the series. They are beloved by AFOLs thanks to their size, exclusivity, interesting and challenging building techniques, and of course rare parts. The name Modulars comes from the fact that you can add extra storeys to your building by buying more pieces to replicate floors. A set which some also consider a Modular is 10190 Market Street which was designed by Dutch AFOL Eric Brok and released by TLG in 2007. 

Moulds

The huge moulds which have molten plastic injected inside to create elements. They are incredibly sophisticated and expensive lumps of metal! Sometimes by extension, AFOLs refer to parts as moulds, e.g. "is that a new mould?"

NCS

Neo Classic Space. A fan building style heavily based on the 'Classic' period of Space sets, which TLG produced from 1979 to 1987. Learn more at Neo Classic Space.

NPU

Nice Part Usage. A compliment employed by peers when a builder uses a part in a surprising, novel, unexpected way. AFOL Tim Gambort defined it well, with pictures, on The Brothers Brick, and then there was some funny comments scrapping.

Polybags

These are the small models that come in little plastic bags. They're often for promotional purposes and not released consistently globally, which is a carrot on a stick to certain collectors! Starting from around the beginning of 2024, polybags were replaced with what The LEGO Group term "paper-based bags", which means paper bags with a thin plastic lining.

POOP

Parts Out of Other Parts. A poor acronym, but given it's a bit rude, it's popular. It refers to those parts that cause strong emotions in AFOLs because they could be built from several smaller parts, which is taken as evidence of dumbing-down of the LEGO® System. Usually referenced during discussions that begin, "when I were a lad..."

Prints, decorations or decals

Elements with printing on them.

Q-Parts

An internal production designation within TLG that is given to all LEGO® elements that are out of production. This just means they are not being produced at this moment and you can't get replacements officially from TLG, not that they are necessarily concepts, rare or permanently retired, despite a lot of fans using the term to describe rare elements which were never available through a LEGO set or other retail channels.

RLUG,  RLFM and RLOC

See LUG.

Rories

A British AFOL nickname for 2x4 bricks that is so friendly and natural it stuck immediately for many. It's not widely used outside of the UK, given that it is quasi-Cockney rhyming slang. Back in the 1960s on east London street markets where LEGO construction was a popular way of filling in downtime for market traders, you could hear banter such as "pass us a two-by-foury guv, I'm building some apples today". The name soon mutated into 'rory' but never made the usual linguistic development of the rhyming word being dropped altogether in favour of another word in a rhyming phrase, although there were isolated incidents of the bricks being named 'Bremners' in the early 2000s. If you'd like to read more about this, you'll need to write your own porkies.

SNOT technique

Studs Not On Top. Many elements have the little building studs on the sides of bricks. This enables 'sideways building' (as TLG prefer to call it) at 90° but there are many methods of building at 180° also. SNOT technique is perhaps to be considered the cornerstone of advanced building, allowing exciting new possibilities and finer detailing.

STAMP

STicker Across Multiple Parts. Instructions that require stickers to be applied over multiple parts is a particularly disliked practice as it makes the parts impossible to separate and use again. The practice has been avoided by TLG for a very long time now.

System

Today the word System refers to groups of elements that are designed to connect together. Today the LEGO Group produce three Systems; the LEGO® System, The LEGO® DUPLO® System and the LEGO® Technic System (even though many Technic elements can also connect to the LEGO System).
The word derives from the term System i Leg (System in Play, or System of Play); a concept developed by Godtfred Kirk Christiansen in the mid-1950s that transformed the company. It focused their attention on the interlocking brick and how that could form the basis of an infinite range of compatible toy products. A great summary can be read at Brick Fetish.

Tablescraps

Those little LEGO® builds that are just to explore an idea, even if it doesn't go anywhere. Usually accompanied by the thought, "that's cool. I must use that in a MOC..."

Technic

The LEGO® Technic System of elements was introduced in 1977 and still runs successfully today. It consists of parts like gears, axles, pins etc. enabling functional mechanical models to be built. Although it appears in so many LEGO® sets, it is not 100% compatible with regular LEGO® System parts.

TLG

The LEGO Group. The official company name.

WOAFOL

Widow/Widower of Adult Fan of LEGO. Pronounced as in 'woeful'. The long-suffering partner that accepts, to some degree, that there are three people in their relationship... well, two people and a bunch of plastic.