An unintentional mistake in speaking, usually trivial, sometimes amusing

I'm sorry Martha, I didn't mean to call your boyfriend honey. It was a slip of the tongue

Scusami Marta, non intendevo chiamare amore il tuo ragazzo. È stato un lapsus

I met my new neighbor, Mr. Fattys, but I greeted him by calling him Fatso. Clearly it was a slip of the tongue, but he got mortally offended by that!

Ho incontrato il mio nuovo vicino di casa, il sig. Ciccone, ma l'ho salutato chiamandolo Ciccione. Chiaramente è stato un lapsus, ma lui si è offeso a morte

In the early 1700s, realizing that people make mistakes also in speaking and not only in writing, the new expression “a slip of the tongue” was created on the model of the previous long-used phrase “a slip of the pen”, which had been around since the mid-1600s