Ancillary means providing support or assistance to something more important, like a helper to the main event. When something is ancillary, it's useful and often necessary, but it plays a supporting role rather than taking center stage.

In a hospital, doctors provide the primary medical care, while ancillary services like X-rays, physical therapy, and lab tests support that care. These services are essential, but they work alongside the doctors rather than replacing them. In a school, the library and computer lab might be considered ancillary facilities that support the main work of teaching and learning in classrooms.

You might hear about ancillary equipment for a camera: tripods, extra lenses, and memory cards that make the camera more useful but aren't the camera itself. A movie might have ancillary characters who help tell the story but aren't the main heroes.

When you describe something as ancillary, you're recognizing its value while also making clear that it supports something else rather than being the primary focus.