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"haggle, bargain in a petty way," 1802, American English, perhaps from dicker (n.) "a unit or package of tens," especially hides (attested from late 13c.), perhaps from Latin decuria "parcel of ten" (supposedly a unit of barter on the Roman frontier; cf. German Decher "set of ten things"), from decem "ten" (see ten) on model of centuria from centum.