What macOS is based on (4)
I believe the answer is:
unix
(Other definitions for unix that I've seen before include "See this operating system" , "software" , "Computer open operating system" .)
I've seen this clue in the Newsday.com and The New York Times.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.