IPA: /ˌæstrəˈnɔtɪk/
KK: /ˈæstrəˌnɔtɪk/
Relating to the science and technology of space travel and exploration.
The astronautic achievements of the last decade have expanded our understanding of the universe.
Astronautic is formed from "astro-" (meaning star, from Greek "astron") and "nautis" (meaning sailor, from Greek "nautes"). The word describes something related to the sailing or traveling among the stars.
Think of a 'sailor' ('nautis') navigating through 'stars' ('astro-') — that's why astronautic relates to traveling among the stars.