v.1. To strike some pair or set of things against each other abruptly: We didn't have a drum to keep the beat, so I knocked a couple of sticks together. The guide showed us how to start a fire by knocking together certain kinds of rock.
2. To collide, especially repeatedly or glancingly: The two boats knocked together in the narrow channel.
3. To make, assemble, or build something quickly or carelessly: The editor knocked an article together for the front page. I knocked together a makeshift table out of some old lumber.