1. To collide into someone or something with great, violent force. The poor kid was racing around the house and smashed into the coffee table at full speed. A cyclist smashed into me on the way to work this morning. I think I may have a cracked rib!

2. To cause someone or something to collide into someone or something with great, violent force. In this usage, a noun or pronoun is used between "smash" and "into." The driver lost control of the vehicle and smashed it into the side of a building. The professional wrestler picked up his opponent and smashed him into the mat.