The Spanish word 'cuchillo' (meaning 'knife') traces its origins back to the Latin word 'culter', which also meant 'knife'. This evolved into the diminutive Latin form 'cultellus', meaning 'small knife'. As the word made its way into Old Spanish, it became 'cuchiello', and finally evolved into the modern Spanish 'cuchillo'. The transformation from 'cultellus' to 'cuchillo' shows typical sound changes from Latin to Spanish, including the softening of the 't' sound to 'ch' and the simplification of the ending.

While 'cuchillo' itself is a common Spanish word, you might encounter related terms like 'cuchillada' (meaning 'slash' or 'knife wound') and 'cuchillero' (meaning 'knife maker' or 'cutler'). These words are built from 'cuchillo' as their base form.

English speakers might recognize a connection to the word 'cutler' (a person who makes or sells knives) and 'cutlery', which both come from the same Latin root 'culter'. While the Spanish word maintained its specific meaning of 'knife', the English derivatives broadened to include various cutting implements and eating utensils.