Definitions of collateral:

• noun:   a security pledged for the repayment of a loan
• adjective:   descended from a common ancestor but through different lines

  Example: "Cousins are collateral relatives"

• adjective:   situated or running side by side

  Example: "Collateral ridges of mountains"

• adjective:   accompaniment to something else

  Example: "Collateral target damage from a bombing run"

• adjective:   serving to support or corroborate

  Example: "Collateral evidence"