My dictionary, for when the Urban Dictionary doesn't have it or gets it wrong.

AR   Any of numerous autoloading rifles using the AR-15 design and generally having mostly interchangeable parts. Vilified by an abysmally ignorant and dishonest state-run media as AR-15s or just ARs. Most believe 'AR' stands for "automatic rifle" but the knowledgeable know it refers to Armalite, the designer of the rifle.