Lamb"da*cism (?), n. [L. lambdacismus, Gr. &?;, fr. la`mbda the letter lambda (Λ).] 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.

• idiosyncratic pronunciation of certain letters.