To drive forward; to urge or press onward by force; to move, or cause to move; as, the wind or steam propels ships; balls are propelled by gunpowder.

to cause something to move forwards.

cause to move forward with force; "Steam propels this ship"

Propel is an object persistence layer for PHP5 based on Apache Torque. In practical terms, it allows you to use objects instead of SQL to read and write rows in your database tables. It provides a generator that creates SQL definition files and PHP classes for your datamodel, and a runtime engine that transparently handles object persistence and retrieval.