The Spanish word 'blanco' meaning 'white' comes from the Proto-Germanic word '*blank', which meant 'shining' or 'white'. This is a relatively straightforward evolution where both the form and meaning remained quite stable over time. The main change was the addition of the '-o' ending to make it conform to Spanish word patterns.

Some related Spanish words include 'blanquear' (to whiten or bleach), 'blanquecino' (whitish), and 'blancura' (whiteness). These words are all derived from 'blanco' and maintain the core meaning related to the color white.

English speakers might recognize the connection to the word 'blank', as in a blank page, which comes from the same Proto-Germanic root '*blank'. While modern English 'blank' has shifted to mean 'empty' or 'void', it originated from the same concept of something being white or shining - think of an empty white page. The English word 'blanch' (to whiten by removing color) is also related and maintains a meaning closer to the Spanish 'blanco'.