From an unused root (compare dakah); crushed, i.e. (fig.) Injured -- afflicted, oppressed.
see HEBREW dakah
H1790. dak
דַּךְ adjective crushed, oppressed — דַּךְ Psalm 74:21; דָּ֑ךְ 9:10; 10:18; plural suffix דַּכָּ֑ו Proverbs 26:28 (Baer; and other editions דַּכָּיו) — in poetry; always figurative, oppressed, distressed Psalm 9:10Psalm 18 ("" יתום) 74:21("" עָנִי and אביון); Proverbs 26:28 דַּכָּו = those crushed by it (a lying tongue).