The antonym of decrease is increase. It means to make something bigger or more significant. If there is an increase in economic activity, it means that the economy is growing. Increase also means to multiply or augment, such as seeds increase and become plants. Another antonym for decrease is amplify. To amplify means to enhance, enlarge or to give greater importance to something. In contrast, decrease means to reduce something, whereas increase means to augment, amplify or escalate it. Depending on the context, an antonym for decrease can be beneficial or adverse, as it can affect people's livelihoods, income, and personal lives.