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