money paid by a tenant to a landlord as a security deposit
Key money may retained against outstanding rent and excessive damage.
money paid by a tenant to a landlord in exchange for a set of keys
The non-refundable sum of £40 is payable as key money.
money paid to an existing tenant who transfers the lease to a new tenant at below the market rate
In France, the new tenant essentially buys the lease from the original tenant by paying key money.