Cush: Cush signifies black, an epithet, in all languages, when applied to the mind, expressive of moral turpitude; and therefore probably here applied to Shimei, denoting that he was a calumniator and villain.
O: Psa 13:3, Psa 13:5, Psa 18:28, Psa 30:2, Psa 30:12, Psa 43:4, Psa 89:26; Jos 14:8; Jer 31:18; Dan 9:4, Dan 9:19-20; Zec 14:5