That which fills a gap or hiatus.

A temporary measure or short-term fix used until something better can be obtained; that which serves as an expedient in an emergency; a band-aid solution.

“The small company uses their old product with a few kludged enhancements as a stopgap until they can develop a new product.”

Filling a gap or pause.

Temporary; short-term.

“They put a stopgap solution in place, but need something more permanent.”