- The definition of a slip up is a mistake or error.
An example of a slip up is when you mix up numbers in a report you are writing and write "12" when the number should be "21."
- an error or oversight
- an unlucky happening; mishap
Also written slipup
An error; an oversight.
- Alternative spelling of slip-up.
- pi-plus, pupils, suppli
NounSee also: slip up