A proponent is someone who actively supports and argues for a particular idea, policy, or cause. The word comes from a Latin verb meaning “to put forward,” and that's exactly what proponents do: they put ideas forward and try to convince others.

If your teacher suggests that the class should spend more time on group projects, she's a proponent of collaborative learning. Environmental activists are proponents of protecting natural habitats. When a town debates building a new skate park, the skateboarders who speak at the town meeting are proponents of the plan.

A proponent doesn't just quietly agree with something: they make their position known and work to persuade others. Scientists might be proponents of a new theory, presenting evidence to support it. Students can be proponents of longer recess, gathering signatures on a petition.

The opposite of a proponent is an opponent, someone who argues against an idea. When people debate important decisions, understanding what the proponents and opponents each believe helps you think through the issue more clearly.