asto noun "dust" (ÁS-AT). According to VT45:6, asto was the name of tengwa #13 in the pre-classical system presupposed in the Etymologies, but Tolkien would later change the name of this letter to anto (its Quenya value changing from st to nt).
Quenya
mul-
verb. grind
mul-
verb. to grind, *pulverize
asto
dust
mól
slave, thrall
mól noun "slave, thrall" (MŌ, VT43:31)
mól
noun. slave, slave, [ᴹQ.] thrall
A noun meaning “slave” or “thrall”, from primitive ✶mōl derived from the root √MŌ having to do with “labour” (VT43/31; Ety/MŌ).
Conceptual Development: In the Qenya Lexicon from the 1910s the word for “slave” or “servant” was ᴱQ. virt or vartyo, derived from the root ᴱ√VṚTYṚ “serve” (QL/102). In the two variants, either the [[eq|short syllabic [ṛ] became [ir] before palatalized [tʲ]]], or [[eq|long syllabic [ṝ] became [ar]]]. This word appeared as an element in the name ᴱQ. Virtinoldor “Thrall-Noldoli” for those Noldor enslaved by Melko(r) in the early tales (PE14/9).
In the Gnomish Lexicon from the same period, another Qenya word for “slave” or “servant” was given as ᴱQ. norka derived from primitive ᴱ✶norokā́ (GL/31), though its relationship to other roots is unclear.
The form ᴹQ. mól first appeared in The Etymologies from the 1930s, already having the derivation given above (Ety/MŌ). This word also appeared in Tolkien’s later writings from the 1950s (VT43/31). A later term for "Slave Noldorin” was ᴹQ. Mólanoldorin (Ety/MŌ; LR/177), a strong indication that mól replaced Early Qenya virt.
mul- vb. "grind", pa.t. múle (QL:63)