'Obscure' shares its PIE root with 'sky,' 'hide,' and 'house' — all from *skeu- (to cover).
Not clearly expressed or easily understood; not well known or prominent; dark or dim.
From Old French 'obscur' and directly from Latin 'obscurus' (dark, shadowy, covered over, hidden, not easily understood), composed of the prefix 'ob-' (over, against, covering) + a root connected to PIE *(s)keu- (to cover, to conceal, to hide). This PIE root is extraordinarily productive: Old English 'sceo' and 'scua' (shadow, shade) derive from it; Greek 'skytos' (leather, hide — that which covers the body) comes from a parallel branch; Old Norse 'sky' (cloud — the covering of the sun) gave English 'sky' (which originally meant the cloud layer covering the earth rather than the blue above it); and from Proto-Germanic *husan (a covering structure) came 'house' and 'hut.' From the same
The PIE root *(s)keu- (to cover) produced wildly different words in different languages: Latin 'obscurus' (dark, hidden), but also English 'sky' (via Old Norse, originally meaning 'cloud-cover'), 'hide' (skin covering), and 'house' (a covering structure). Darkness, clouds, skin, and shelter are all 'coverings.'