Ilk. initial [s] was lost before consonants; [sC-] > [øC-]
This rule is described on the Comparative Tables along with the unvoicing effects of the initial [s] (PE19/20-21), but in The Etymologies the only examples are [st-] > [θ-] (see below).
|After||02300||initial [s] unvoiced following [l], [r], [w]||ᴹ✶sl- > Ilk. lh-||PE19/21|
|After||02400||initial [s] spirantalized following voiceless stops||ᴹ✶stalrā > Ilk. thall||Ety/STAL|
Phonetic Rule Elements
||✧ PE19/21 (sm- > m-); PE19/21 (sn- > n-)|