'Lallation' definitions:

Definition of 'lallation'

(from WordNet)
noun
Defective articulation of the `l' phoneme or the phoneme `r' is pronounced as `l'
noun
Gibberish resembling the sounds of a baby [syn: babble, babbling, lallation]

Definition of 'Lallation'

From: GCIDE
  • Lallation \Lal*la"tion\, n. [L. lallare to sing lalla, or lullaby: cf. F. lallation.] An imperfect enunciation of the letter r, in which it sounds like l. [1913 Webster]