The Thracian word ukas
Word ukas
Meaning mist
See also Attic Greek: ἀχλύς ‘mist, fog’

Other words that might be of interest
dumas ‘dark’, gaidrus ‘bright, clear’, sartas ‘light-red’, titha ‘light, radiance’, zbel- ‘shining’, zburul ‘light’, zvaka ‘bright’