The term "activator" can refer to different things depending on the context. Here are some possible meanings:

• In dentistry: An activator is a removable appliance, usually made of hard plastic, that is worn in the mouth to help align teeth and improve their relationship.

• In chemistry and biochemistry: An activator is a catalyst, a substance that increases the rate of a chemical reaction without being consumed in the process.

• In DIY slime making: An activator is a substance that is added to glue and other ingredients to create slime. Common activators include borax, contact lens solution, and liquid starch. There are many recipes available online for making slime activators at home.