correction
/kəˈrɛkʃ(ə)n/
noun
the action or process of correcting something.
the meaning is clear enough!
the market is filled with traders, and traders want profit. they buy in order to sell. when price goes up, they sell and selling means price will come down. this downward movement (dip, drop,...) is called correction.
the demand in total is what keeps the price up and increases it over time. the traders who buy and sell are only some part of the market. for bitcoin they are bigger part and since the market itself is smaller, the corrections become big from time to time.