Downswing
A downswing is a period in which a player loses more than expected over a long stretch of play.
The simple explanation
A downswing is a series of losses over many sessions. It is normal in poker. Even the best players lose over stretches of weeks or months, because the cards go against them. The word is the opposite of an upswing.
A closer look
Downswings are a result of variance. Winning players can have losing months or even years. The way to handle one is to check that the decisions are good, keep playing within your bankroll, and avoid tilt. Moving down in stakes is a common response when the bankroll shrinks, and the ratio of buy-ins to stakes matters.
A practical example
A player wins at 4 bb/100 on average but loses 10 buy-ins over 10,000 hands. That is a downswing.
Full explanation
A downswing is a period in which a player loses more than expected over a long stretch of play.
A downswing is a series of results totaling an overall loss, such as over multiple sessions or a particular period of time. Unlike a single bad session, it is spread over a long stretch.
It is an expected part of poker. The bigger the sample, the less luck matters, but even over thousands of hands a good player can lose.
Handling it well is a skill of its own. Players track their results, check their play, and control tilt. They also keep to their bankroll rules so that a downswing does not force them to quit.
The opposite is an upswing, a period of better results than average.
Alternative spelling: down swing, down-swing