Where does “космонавт” come from?

космонавт (Ukrainian) comes from Ancient Greek ναύτης, from Ancient Greek -τής, from Ancient Greek πεῖρα, from Proto-Indo-European per-, from Proto-Indo-European pr̥tós — passed , crossed.

космонавт (Ukrainian): cosmonaut

Definitions

cosmonaut

Ancestry of “космонавт”, step by step

космонавт traces back through two separate lines of ancestry.

via Ancient Greek ναύτης

Step	Language	Word	Meaning
1	Ancient Greek	ναύτης	sailor, seaman; companion at sea
2	Ancient Greek	-τής	Appended to verbs to form agent nouns
3	Ancient Greek	πεῖρα	trial, experiment, attempt
4	Proto-Indo-European	per-	before, in front; first; to go through
5	Proto-Indo-European	pr̥tós	passed , crossed

via Ancient Greek κόσμος

Step	Language	Word	Meaning
1	Ancient Greek	κόσμος	order; lawful order, government; mode, fashion
2	Ancient Greek	θέσις	a setting, placement, arrangement; deposit;...
3	Ancient Greek	τίθημι	I put, place, set; I make, cause to be; I make
4	Proto-Indo-European	dʰeh₁-	to do, put, place

Every word from Proto-Indo-European pr̥tós →Every word from Proto-Indo-European per- →Every word from Ancient Greek -τής →