The Spanish word 'tres' meaning 'three' comes directly from the Latin word 'tres', which also meant 'three'. This is one of the most stable words in Indo-European languages, maintaining nearly identical form and meaning over thousands of years.

Some common Spanish words derived from 'tres' include: 'tercero' (third), 'treinta' (thirty), 'triple' (triple), and 'triángulo' (triangle). All these words maintain a connection to the concept of 'three' in their meanings.

English has many cognates related to 'tres' through the shared Indo-European root, including 'three', 'third', 'thirty', and 'triple'. While English 'three' might look quite different from Spanish 'tres', they are actually related words that evolved differently in Germanic (English) versus Romance (Spanish) languages. The English word 'tri-' (as in 'triangle', 'tricycle', 'trilogy') is a prefix borrowed from Latin that's directly related to 'tres'.