"Timed trials" refers to tests or competitions where participants are measured based on how quickly they can complete a task or reach a goal within a specific period of time. Full definition
Throw in co-op mode and the simple thrills of time trial mode and you've got good value for money. (wolfsgamingblog.com)
In time trial levels you control the speed of enemies whilst trying to finish the level as quickly as possible. (idatxbox.com)
In addition to the main story line there are time trials for each level where you can compete against your friends to see who can complete levels the fastest. (andymerrill.com)