When you buy a security, such as a stock or ETF, the original price you paid is often referred to as the cost basis. If you bought shares at different prices, the price you’ve paid per share is shown as the average price (shortened to Avg. price in the Edge platforms).
When you view the average price, add any reinvested amounts (through a DRIP or distributions, for example), and any fees, the final amount calculated is known as the adjusted cost base (ACB).