لثفلُثْفَةٌ The changing, in pronunciation, س into ث, or ر into غ or ل, (S, K, Msb,) and the like: (Msb:) or, one letter into another. (Az, in Msb, K.) Also, A word mispronounced; as when a word is said to be لُغَةٌ أَوْ لُثْفَةٌ a dialectal variant or a word mispronounced.