collateral Look up collateral at Dictionary.com
late 14c., "accompanying," also "descended from the same stock," from O.Fr. collateral, from M.L. collateralis "accompanying," lit. "side by side," from L. com- "together" + lateralis "of the side," from latus "a side" (see oblate (n.)). Lit. sense of "parallel, along the side of" attested in Eng. from c.1450.