A security or guarantee (usually an asset) pledged for the repayment of a loan if one cannot procure enough funds to repay.

(genealogy) A collateral (not linear) family member.

A branch of a bodily part or system of organs.

“Besides the arteries blood streams through numerous veins we call collaterals.”

Parallel, along the same vein, side by side.

Corresponding; accompanying, concomitant.

Being aside from the main subject, target, or goal.

“Although not a direct cause, the border skirmish was certainly a collateral incitement for the war.”