from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A slip of the pen, a miswriting.
From Latin lapsus ("lapse") + calami ("of the pen"), genitive of calamus. Literally meaning "slip of the pen". (Wiktionary)
Nonetheless, your resident Latin censor—dash it all—must have been dozing when he allowed a certain lapsus calami aka “slip of the pen” to pass his watchful eye.