Slip-Up Meaning

(idiomatic) A mistake or error; a minor misstep.

Example:   I think she will forgive an accidental slip-up, so don't worry too much about misspeaking.
2012 June 29, Kevin Mitchell, “Roger Federer back from Wimbledon 2012 brink to beat Julien Benneteau”[1], the Guardian:
  For the second year in a row at Wimbledon, Roger Federer went to five sets against a Frenchman but this time there would be no slip-ups.