ad D. Greene, in Ériu 33 (1982), pp. 163-164. Suggests a correspondence with Lat. nitrum and that sléic meant potash, as a personal detergent, and perhaps also a coloured, friable salt used as a cosmetic.
Lat. lodix glossed with Ir. sléic (means ‘pumice’, possibly related to slíachtaid ‘smoothes’), ruamnae (earlier form of rúamna ‘colouring matter, redish colour’), diol (‘fillet, diadem’): all exx. of ornamentum muliebre. Also suggests Ir. slíogadh ‘smoothing, polishing’ derives from ON slíkja ‘to smoothe’, although slíocadh forms may have been influenced by Engl. slick ‘to slick, polish, smooth’.