a slip of the tongue/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!
See also: of, pen, slip

slip of the tongue

A small mistake made when speaking. I accidentally called John by his brother's name. It was just a slip of the tongue. The news anchor's innocent slip of the tongue has gone viral, of course.
See also: of, slip, tongue
Farlex Dictionary of Idioms.

slip of the tongue

an error in speaking in which a word is pronounced incorrectly, or in which the speaker says something unintentionally. I didn't mean to tell her that. It was a slip of the tongue. I failed to understand the instructions because the speaker made a slip of the tongue at an important point.
See also: of, slip, tongue
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

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.
See also: of, pen, slip

a slip of the tongue

A slip of the tongue is something that you said by mistake. At one stage he referred to her as James's `fiancée' but later said that was a slip of the tongue and that they were not formally engaged.
See also: of, slip, tongue
Collins COBUILD Idioms Dictionary, 3rd ed.

slip of the pen (or the tongue)

a minor mistake in writing (or speech).
The equivalent Latin phrases, lapsus calami and lapsus linguae , are also sometimes used in formal English.
See also: of, pen, slip
Farlex Partner Idioms Dictionary

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.
See also: of, pen, slip, tongue
Farlex Partner Idioms Dictionary
See also:
  • a slip of the pen
  • slip of the pen
  • slip of the lip
  • eat (one's) shirt
  • I tell a lie
  • suite
  • tout de suite
  • tout suite
  • garbage in, garbage out
  • two whoops and a holler