d20 

A 20 sided die used in many games in the "Dungeons & Dragons" series of tabletop role-playing board games.

Carl: Say Falacorn, let's break out the d20 and set us up a game of *gasp* DUNGEONS AND DRAGONS.
Joe: Indeed Yeldor, but I call dungeon master!
*slap fight ensues*

d20 by Wesley Durrance August 13, 2005

d20 

A twenty sided die, or a system which has been used to base games off of. Also damages the Dungeon Master's walls after rolling low many consecutive times.

Player: Sonofabitch! Another 1?! How dare you betray me?!

*Throws d20 in a random direction as hard as he can*

Dungeon Master: Goddamnit Joe! That's the fourth time you've done that! I'm sure as fuck not paying if there's any damage!

d20 by Kerik July 12, 2006

d20 

1: A 20 sided die. 2: A gaming system devloped to play Dungeons and Dragons and other table-top RPGs.

1: Roll a d20.
2: We could play Star Wars d20 or Modern d20.

d20 by Ryan March 2, 2004

D20 

A 20 sided die that dm’s use to infuriate their players.

Dm: roll arcana
Leon: are you fucking kidding me
Jim: did it roll low again?
Leon: IT ROLLED A FUCKING 3 AGAIN
Emma: just get better a better d20
Leon: fuck you

D20 by Car’s son March 23, 2021

d20 

A 20 sided die

roll a d20

d20 by d00d June 13, 2003

d20 

The first open Liscense gaming system.

Yet another gaming system that held great potential but was ruined by over priced books , Unthought out rules, and market whoring.

Have you see the new d20 version of Cuthlullu

d20 by Telos March 2, 2004

d20 

A 20 sided die to keep track of your life total in Magic, the Gathering.

Where is my d20, I need to keep track of my life total.

d20 by McDutch August 10, 2008