Definitions

1. noun

A person who is an expert in an extraneous or auxiliary subject; a specialist in a related or tangential field.

“The team of experts included an exostra on ancient civilizations who provided a unique perspective on the cultural context of the discovery.”

2. noun

Something that is added or attached to something else, especially in a superficial or auxiliary manner.

“The new software feature was an exostra to the existing platform, allowing for more seamless integration with other tools.”