mītha

adjective. *grey

thin

root. *grey

Tolkien introduced the (unglossed) root ᴹ√THIN in The Etymologies of the 1930s with derivatives like ᴹQ. sinde/N. thinn “grey, pale” and ᴹQ. sinta-/N. †thinna- “fade” (Ety/THIN). In this document it was the basis for the name Ilk. Thingol; in earlier writings from the 1920s the name ᴱN. Thingol was based on the word ᴱN. thing “prince” (PE13/154). The root √THIN or √ΘIN was mentioned a couple times in Tolkien’s later writings as the basis for “grey” words (PE17/72; WJ/384). In a note from the mid-1960s Tolkien considered making the root √STIN the basis for “grey”, as a privative formation = √S-TIN = “without sparkling” (PE17/184), but I think this was a transient idea.