Blue-Chip Stocks: Refers to the stock of a well-established and financially sound company that has been in operation for many years. Having a market capitalization in the billions, a blue-chip stock is typically a market leader or top company in its sector. Most blue-chip stocks have paid stable or rising dividends over the years. It is believed that blue-chip stock is a reference to poker, where blue chips are the most expensive.
Source: Investopedia