Where does “sonrojar” come from?

sonrojar (Spanish) comes from Spanish Rojo, from Spanish rojo, from Latin russeus, from Latin russus, from Proto-Indo-European h₁rewdʰ- — red.

sonrojar (Spanish): to cause to blush

Definitions

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