קָדַרvb. be dark (dull-coloured, cf. Ar. Arabicbe dirtyQalbe darkHiph1darken2cause to mournHithp. and the heavens grew dark with clouds.
Strong Concise Dictionary Of The Words In The Hebrew Bible
H6937קָדַרqâdar; a primitive root; to be ashy, i.e. dark-colored; by implication, to mourn (in sackcloth or sordid garments) — be black(-ish), be (make) dark(-en), × heavily, (cause to) mourn.