What does buying on margin mean?

buying on margin meaning in Law Dictionary

In finance, a margin is collateral your owner of a financial tool has to deposit to cover some or most of the credit chance of his counterparty (most frequently his agent or an exchange).

buying on margin meaning in Business Dictionary

Purchasing a secured item by simply making a down repayment (called the margin) and funding the total amount quantity through financing by using the asset while the security (eg in a mortgage loan). In securities trading, only a down repayment is necessary since the worth of the securities by themselves (which stay in the ownership associated with broker or seller) completely collateralizes the unpaid quantity.