a stock market that is experiencing an increase in stock prices (in general/aggregate/category/etc.).
the increase is often attributed to:
(i) investor optimism; and/or
(ii) a booming economy.
It can affect the entire stock market index (eg, the S&P 500); or it can affect individual stocks.
the benchmark for the increase is often set at a 20% rise;
the duration of the increase is typically set at multiple months (or even years)