A correlative appearing in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/111), a combination of ᴹQ. si “this” and the similative suffix ᴹQ. -ndon.
Qenya
sindo
masculine name. The Grey
sindon
adverb. like this
si
pronoun. this
An earlier variant of Q. Singollo glossed “The Grey” (LR/215, MR/088), apparently a masculinized form of the adjective sinde “grey” (Ety/THIN).