a slip of the pen
slip of the pen
An unintentional mistake in one's writing, such as incorrect spelling, word choice, or meaning. Whoops, I meant to tell my mother that she was welcome to call over next Monday, but I actually wrote "next month" instead. Oh well, she'll understand that it was just a slip of the pen. Now take your time while writing these test essays—you don't want a few slips of the pen to be the reason you get a lower grade!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a slip of the pen
A slip of the pen is something you wrote by mistake. The translator dated his letter `Plymouth 1 June 1618'. This is wrong, and probably a slip of the pen for 11 June.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
a slip of the ˈtongue/ˈpen
a small mistake when speaking or writing: Did I say North Street? Sorry, that was a slip of the tongue — I meant South Street.Farlex Partner Idioms Dictionary © Farlex 2017