Where does “Semifinal” come from?

Semifinal (German) comes from German final, from Latin fīnālis, from Latin -ālis, from Proto-Italic -ālis — forms relational adjectives.

Ancestry of “Semifinal”, step by step

StepLanguageWordMeaning
1Germanfinalfinal; expressing purpose; final; conclusive;...
2LatinfīnālisOf or pertaining to boundaries
3Latin-ālis—
4Proto-Italic-ālisforms relational adjectives
Every word from Proto-Italic -ālis →Every word from Latin -ālis →Every word from Latin fīnālis →