Lapsus calami is Latin for 'typo'. It literally means a 'lapse of the pen', and may refer to any transcription error or misspelling. It is used as a technical term in the field of biological nomenclature; any error in a published work is identified by one of a number of very specific terms. As you might expect, lapsus calami is not uncommon when dealing with long Latin names of families, species and various varieties.
Lapsus calami is synonymous with the less poetic and less common sphalma typographicum, literally a 'typographic error'. Despite what many sources will tell you, nomen nullum is not a synonym. A basic list of errors in scientific nomenclature would include:
If one moves away from the field of taxonomy, one might speak of other types of lapsus than those involving typos; a lapsus linguae would indicate that one misspoke, while a lapsus memoriae would indicate that one misremembered. Those, however, belong in other nodes.