peter

To "peter out" means to gradually become weaker or smaller until it stops. Imagine a firework display: it starts with a bright burst of color, but eventually the sparks peter out and disappear. Or think about excitement for a new hobby; you might start strong, but if you do not keep going, your interest could peter out.

This phrase is usually used for things that do not end all at once. They fade little by little. A conversation might peter out when people have nothing more to say. An argument might peter out after both sides get tired. A storm can peter out as the rain slowly becomes lighter and then stops.

The phrase "to peter out" describes the process of something gradually losing strength or momentum until it comes to a halt. It suggests a slow decline rather than a sudden stop. For example: "Their initial excitement about the project began to peter out as they encountered more and more obstacles." Or, "The rain started strongly but quickly petered out to a drizzle."

It's often used when talking about efforts, enthusiasm, or resources that diminish over time. A conversation might peter out if people run out of things to say, or a fundraising campaign could peter out if it doesn't receive enough donations.

The origin of the phrase is uncertain. What matters for learners is the idea: something starts to run out, grow weaker, and end in a slow, quiet way. It is commonly used for activity, energy, sound, rain, support, or interest. You can say a crowd's cheering petered out, a trail petered out in the woods, or someone's motivation petered out after a few weeks.

So whether it's a plan, an argument, a storm, or your motivation, when something begins to peter out, it's losing steam and heading towards its end—often slowly and quietly.