Swooping is a term I (tapir, 2011) like to use to describe the technique some online players use to get even games against stronger players. A extreme form of this technique is on servers, where one can create an account above one's strength. Swoopers can be detected by rapidly decreasing rank graphs, which may stabilize when the server allows free games.
The better technique to get even games against stronger players is called: asking. Just ask for an even game, many don't mind to play without appropriate handicap once in a while.
In the 2020s the name airbagging or, more rarely, helium bagging is (probably) more common, coined in reference to sandbagging.