Slip up is a term used for a mistake or an error. Synonyms for this word are slip, mistake, error, blunder, fault, oversight, slip of the tongue, faux pas, gaffe, boo-boo, blooper, lapse, flub, screw-up, stumble, snafu, miscue, muff, misunderstanding, misconception. All of these words share the same meaning as slip up, describing a mistake or misstep in judgment or action. A slip-up can be a minor mistake or a catastrophic one, but whatever the severity, owning up and learning from the experience is essential for growth and improvement.