Imbalance of Orders

What Does Imbalance of Orders Mean?
A situation when too many orders of a particular type - either buy, sell or limit - for listed securities and not enough of the other, matching orders are received by an exchange. Also referred to as "order imbalance".

Investopedia explains Imbalance of Orders
Shares experiencing an imbalance of orders may be temporarily halted if trading has already commenced for the day. If it occurs prior to market open, trading may be delayed. Better-than-expected earnings or other unexpected good news can result in a surge in buy orders in relation to sell orders. Likewise, unexpected negative news can bring a large sell-off.