1. An opening between two rooms, especially a shelved space between a kitchen and dining room that is used for passing food.

2. A route through which something is permitted to pass.

3. A financial security collateralized by a portfolio of mortgages or other loans, the income from which is passed through an intermediary before being distributed to investors in fixed payments. Also called pass-through security.

4. The policy, practice, or act of paying for an increased cost by raising the price charged to one's customers or clients. Also called pass-along.