1. To get into something, especially a vehicle, all at the same time. Make sure you take a head count after all the kids have loaded into the bus. The passengers began loading into the cruise ship, blissfully unaware of the horror that awaited them in the middle of the ocean.

2. To usher people into something, especially a vehicle, all at the same time. In this usage, a noun or pronoun is used between "load" and "into." We had just loaded everyone into the car when Tommy said he needed to use the bathroom. I hope they start loading us into the plane soon.

3. To put a supply of something into a structure, vehicle, or mode of conveyance. In this usage, a noun or pronoun is used between "load" and "into." Let me know when you're finished loading that timber into the van. We'll need a forklift to load these pallets into the storage unit.