Element – a catch-all term that refers to any one of the many different types of LEGO pieces that are available.
Brick – the basic building block of the LEGO system. It is available in various sizes and colors. The smallest brick is a 1×1 brick which has a square footprint and one stud on its top. It is a little taller than it is wide. The first brick that was invented and patented is the 2×4 brick which has 8 studs in 2 rows.
Plate – the thinner counterpart of a brick. It is only a third as tall (0.32 cm) as a brick.
Stud – the small cylindrical bump that can be found on the top of a LEGO brick or a plate. A stud is also a unit of measurement referring to the center-to-center distance between two neighboring bumps which is 0.8 cm.
Anti-stud – a receptacle for a stud that can be found on the underside of a brick or a plate. This along with the stud (see above) form the interlocking mechanism that allows LEGO pieces to be joined together.
Brick Height – a unit of measurement based on the height of a regular brick which is 0.96 cm.
Clutch Power – how well joined LEGO bricks stay together. One selling point of LEGO bricks is the excellent clutch power these bricks retain even after being joined and taken apart numerous times. This is achieved by the extremely tight tolerances that LEGO uses in their manufacturing process.
Brick Separator – a tool designed to make it easier to separate LEGO pieces that are joined together. It has anti-studs that engage with the studs on a LEGO piece and allow it to be separated without much effort.
Baseplate – a large plate that is typically used as the base for the LEGO build. This is thinner than a regular plate and doesn’t have anti-studs on its bottom. LEGO is in the process of phasing out baseplates in favor of regular plates in their sets.
Tile – a plate with no studs. It has a smooth surface on the top. Since it does not have studs, a tile typically has a groove on its bottom edge allowing it to be removed easily when it is attached to another LEGO element.
Slope – a piece that tapers on one or more sides. Slopes were originally created to be used as roof pieces. These come in both regular and inverted versions.
Cheese Slope – a 1×1 slope piece that gets its name from the fact that it resembles a little wedge of cheese. It is two plates high with a lip at the base of the slope that is half a plate high.
Hinge – an element consisting of two halves that are joined together such that they can swivel with respect to each other.
Turntable – consists of base and a top (a circular plate or brick) attached to it that can swivel freely by a full 360 degrees.
Bracket – a plate with a perpendicular extension that also has studs on it. This allows the direction of building to be changed by 90 degrees.
SNOT – acronym for Studs Not on Top. This is another term for sideways building where LEGO elements are attached to studs on the sides of other elements (rather than the top).
Headlight Brick – a 1×1 brick with a stud on its side (in addition to the one on its top) which is inset by half a plate. It also has an anti-stud on its back making it one of the most unique elements in the LEGO catalog.
Jumper Plate – a 1×2 jumper plate has one stud halfway between where the two studs on a regular 1×2 plate would be located. Similarly, a 2×2 jumper plate has one stud in the center of where the four studs on the regular 2×2 plate would be located.
Half Stud Offset – a technique that allows LEGO elements to be offset by half stud increments. This is achieved by using LEGO jumper plates.
Half Plate and Quarter Plate Offset – techniques than be used to achieve even more subtle offsets than half stud offsets. Half plate offsets can be created using headlight bricks or brackets. When combined with jumper plates and half stud offsets, it is also possible to realize quarter plate offsets.
Illegal technique – technique that uses LEGO pieces in ways that they were not intended to be used. Illegal techniques can put undue stress on LEGO pieces and damage them over time.
Lowell Sphere – a LEGO sphere created by attaching 6 identical panels composed of plates to a SNOT cube. This was invented by Bruce Lowell.
Brick-bending – a technique that creates curved shapes by taking advantage of the natural flex that exists in long walls built using LEGO bricks. Strictly speaking, this is an illegal technique but it can help produce some truly unique LEGO creations.
Scale and Minifig scale – the scale is the relative size of a LEGO model compared to the real-life object it is meant to represent. It is usually expressed as a ratio such as 1/192 where 1 inch in the LEGO model represents 192 inches in the actual object. Minifig scale (around 1/45) is the size of a minifig compared to an average human.
MOC – acronym for My Own Creation – a term used to describe custom models (that are not created by following instructions provided in official LEGO sets).
AFOL – acronym for Adult Fan of LEGO. The first of many such acronyms including TFOL (Teen Fan of LEGO), KFOL (Kid Fan of LEGO), etc.
Stud.io – a software package created by Bricklink (now owned by LEGO) that allows you to design and build LEGO models digitally. Stud.io can also be used to create photorealistic renders, building instructions, etc.