Arbitrage: Simultaneous buying and selling of the same asset in different markets in order to capitalize on variations in price between those markets .
Ask price: Lowest price at which a dealer is willing to sell a commodity.
Assayer: Assayer is an authorized entity (person/institution) that certifies and grades the commodities that are delivered in exchange accredited warehouses.

B
Backwardation: In futures market, when a commodity is in shortage, causing near month contract to sell at a premium and distant month contract to sell at a discount i.e. spot price of the commodity is higher than the forward price.

Bullion: The generic word for gold and silver.

Bar Chart -
A chart that graphs the high, low, and settlement prices for a specific trading session over a given period of time.

Basis -
The difference between the current cash price and the futures price of the same commodity. Unless otherwise specified, the price of the nearby futures contract month is generally used to calculate the basis.

Bear -
Someone who thinks market prices will decline.

Bear Market -
A period of declining market prices.