لكن

لُكْنَةٌ ذ An impotence, or impediment, or a difficulty, in speech or utterance; (Msb;) a barbarousness, or viciousness, and an impotence, or impediment, in speech: (S:) or the not speaking Arabic rightly, by reason of a barbarousness, or viciousness, in the tongue: (K:) or the interposing of [ words of ] a foreign language in one's speech. (Mbr, TA.) See تَهْتَهَةٌ; and عُجْمَةٌ, with which it is syn.