Lambdacism

n.	1.	A fault in speaking or in composition, which consists in too frequent use of the letter l, or in doubling it erroneously.
	2.	A defect in pronunciation of the letter l when doubled, which consists in giving it a sound as if followed by y, similar to that of the letters lli in billion.
	3.	The use of the sound of l for that of r in pronunciation; lallation; as, Amelican for American.

Noun

1.

lambdacism - speech defect involving excessive use or unusual pronunciation of the phoneme `l'

defect of speech, speech defect, speech disorder