Propagation is the process of spreading or multiplying something, whether it's plants, waves, or ideas.

In gardening, propagation means creating new plants from existing ones. You might propagate a spider plant by planting one of its baby offshoots, or propagate a rose bush by cutting off a healthy branch and helping it grow roots. Gardeners who master propagation can fill an entire garden from just a few original plants.

In science, propagation describes how things like light, sound, or radio waves travel through space or materials. When you speak, sound waves propagate through the air to reach someone's ears. When you turn on a lamp, light propagates outward in all directions. Scientists study how quickly different types of waves propagate through different materials. Sound propagates faster through water than through air, which is why whales can communicate across vast ocean distances.

The word can also describe how information or ideas spread through a community. A rumor propagates through a school as students tell each other. News propagates around the world through television, radio, and the internet. When people talk about the propagation of knowledge, they mean how learning and discoveries spread from person to person and place to place.