Level Graphics Resources (?). An LGR file is a file that contains all necessary picture files for the game to work, such as pictures, masks, textures and biker's parts. An LGR can be made or modified with the LGR Development Kit. You can get it directly from alazs's site.
Level (lev, track or map) is a composition of polygons, pictures and objects that forms a playable area for the kuski. Levels are usually made in internal level editor, though there exist other tools for that, see Level editor.
With the level editor it is possible to make your own levels. Besides the game's level editor there's also ALE, an alternative level editor with more advanced options.
Internal editor shows only 1000 levels from the lev folder. This limit has been removed in belma. If you make battle levels, best way to name your levels is like '001', '002' and so on. Don't put spaces in level name; it crashes the level editor.
Levelpack means simply a bunch of levels. Usually all the levels are made by same person/persons and they are named consistently. In elma 1.2 there is an option which allows to make levelpacks with level name pattern. With that, you can generate statistics automatically. Examples for famous levelpacks are ALP (Alternative Level Pack), OLP (Official Level Pack), RLP (Russian Level Pack) and IFLP (Internal Feeling Level Pack).
Level Of the Month. A contest organized by Moposite which is all about level designing. Every month a new theme is released and the designers have one month to make the best level possible about that theme. The levels are rated on these points: visual, playability, respect of theme and name. The contest have been on pause since 2003. See LOM section.