Feminine passive participle of Anammelek in the sense of a bargain or exchange; something given as security, i.e. (literally) a token (of safety) or (metaphorically) a bondsman -- pledge, surety.
see HEBREW Anammelek
H6161. arubbah
עֲרֻבָּה noun feminine thing exchanged, pledge, token; — suffix עֲרֻבָּתָם 1 Samuel 17:18 = a token from them, i.e. response, token of welfare, Th Dr and others; absolute as accusative of congnate meaning with verb ע ׳עָרַב Proverbs 17:18 give a pledge.