Where does “Rojo” come from?

Rojo comes from Spanish rojo, derived from Latin russus meaning "red," which traces to Proto-Indo-European h₁rewdʰ- meaning "red."

Ancestry of “Rojo”, step by step

Step	Language	Word	Meaning
1	Spanish	Rojo	red colour
2	Spanish	rojo	red; a 1000 colón bill; Red; a left-winger,...
3	Latin	russeus	dark red
4	Latin	russus	red, reddish-brown
5	Proto-Indo-European	h₁rewdʰ-	red