lambdacism

noun

lamb·​da·​cism ˈlam-də-ˌsiz-əm 

1

: excessive use of the letter l or the sound \l\ (as in alliteration)

2

: a defective articulation of \l\, the substitution of other sounds for it, or the substitution of \l\ for another sound compare lallation sense 2, paralambdacism