Other forms: mixers
A mixer is a device used for blending things together, like a cement mixer or the countertop mixer you use when you bake cookies.
The word mixer is used for many different things, but they all have some element of combining or blending something together. When a social event is described as a mixer, it's meant to bring diverse groups together, giving them the opportunity to meet people they might otherwise not cross paths with. And a DJ's mixer is an electronic device that's used to combine audio signals so they can create smooth transitions from one song to the next.