: something that you promise to give someone if you cannot pay back a loan
She put up her house as collateral for the loan. [=she agreed that she would give up her house if she did not repay the loan]
formal
: related but not in a direct or close way
collateral relatives
the collateral effects of the government's policies
Cite this Entry
“Collateral.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/collateral. Accessed 23 Jun. 2026.
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