The Spanish word 'rubor' comes from the Latin word of the same spelling, 'rubor', meaning 'redness' or 'blush'. This Latin noun was formed by combining the verb 'rubere' ('to be red') with the suffix '-or', which was used to create nouns indicating a result or effect. So literally, 'rubor' meant 'the result/effect of being red' - a blush or redness.

Some related Spanish words include 'rubio' (blonde), 'rubí' (ruby), and 'rojo' (red), all of which share the same Latin root related to redness. While 'rubor' specifically refers to blushing or redness of the face, these related words all maintain the connection to the color red in different contexts.

English speakers might recognize the connection to words like 'ruby', 'rubicund' (having a ruddy complexion), and 'russet' (reddish-brown), which all trace back to the same Latin root 'rubere'. The word 'robust' also comes from this root, as it originally referred to the healthy red color of someone strong and healthy.