From raqab; decay (by caries) -- rottenness (thing).
see HEBREW raqab
H7538. raqab
רָקָב noun [masculine] rottenness, decay (always figurative); — ׳ר absolute; apparently of ravages of worm, in יְהוּדָה בֵּית, in figure Hosea 5:12 ("" עָשׁ), compare Job 13:28 ("" id.); elsewhere of decay of bones, caries (in figurative), ׳ר ׳בְּעַצְמ Habakkuk 3:16; Proverbs 12:4, construct עַצְמ ׳רְקֵב 14:30.