Bad writing; bad handwriting. (Opposed to calligraphy).

In the phrases a slip of the pen, a slip of the tongue, etc.

In Palaeography and Textual Criticism: Double writing; the unintentional repetition of a letter or word, or series of letters or words, by a copyist.

The practice or an act of inadvertently writing a letter or word, or series of letters or words, once, when it should have been repeated. Opposed to…

A lapse, slip, or error. Chiefly in the Latin phrases lapsus linguae n. a slip of the tongue, and lapsus calami n. a slip of the pen.