What is the meaning of collateral?

noun

• A security pledged for the repayment of a loan.

adjective

• Descended from a common ancestor but through different lines.
  • usage: "cousins are collateral relatives"; "an indirect descendant of the Stuarts"
  • synonyms: indirect
• Serving to support or corroborate.
  • usage: "collateral evidence"
  • synonyms: confirmative, confirming, confirmatory, corroborative, corroboratory, substantiating, substantiative, validating, validatory, verificatory, verifying
• Accompany, concomitant.
  • usage: "collateral target damage from a bombing run"
• Situated or running side by side.
  • usage: "collateral ridges of mountains"