Definition of 'Up Volume'
A stock volume that closes at a price higher than the previous day's close. Up volume occurs when a stock finishes a day of trading at a level higher than its open, meaning that the trading volume for the day was more bullish than bearish. Traders often watch for instances of up volume as a possible signal for a breakout.
Also referred to as "up on volume."
Investopedia explains 'Up Volume'
If a stock closed at a price higher than the previous day's close, the share volume for that day would be considered up volume. Quite often, market participants refer to a day of overall market up volume as a day of bullish volume, due to an overall bullish sentiment sending markets up. Typically, however, days of down volume are heavier in terms of overall volume than up days.