The Spanish word 'navaja' meaning 'razor' or 'knife' comes from the Latin word 'novacula' meaning 'razor'. The Latin term 'novacula' itself was formed by combining the Latin adjective 'novus' meaning 'new' with the instrumental suffix '-cula'. The connection between 'new' and 'razor' likely stems from the idea that a razor needs to maintain a fresh, new edge to be effective at cutting. As the word evolved from Latin to Spanish, 'novacula' underwent phonetic changes to become 'navaja', with the 'o' shifting to 'a' and the middle syllable being lost.

The Spanish word 'nuevo' (meaning 'new') is a cousin of 'navaja', as they both trace back to the Latin 'novus'. While 'nuevo' retained the original meaning of 'new', 'navaja' developed from a compound word specifically referring to a cutting implement.

English speakers can connect 'navaja' to words like 'novel', 'new', and 'nova', which all come from the same Latin root 'novus'. While these English words maintained the sense of 'newness' or 'innovation', the Spanish 'navaja' evolved along a different path to specifically denote a cutting tool. The word 'innovate' is another English relative that preserves the 'nov-' root meaning 'new'.