Brewer's: Lapsus Linguæ
(Latin). A slip of the tongue, a mistake in uttering a word, an imprudent word inadvertently spoken.
We have also adopted the Latin phrases lapsus calami (a slip of the pen), and lapsus memoriæ (a slip of the memory).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894