You may already be familiar with this one.
Purchase Order: A document that states you have the intent to purchase a good or service and the specifics of the goods requested to be made. As a result the manufacturer or the service can go ahead and begin making your order. It can be legally binding to pay once you place it unless a manufacturer fails to provide you with the requested goods.
In a sentence: “Hey, did you remember to place that PO for the bicycles?”