The Spanish verb 'viajar' (to travel) has its roots in the Latin word 'via', which meant 'road' or 'way'. From this, Latin developed the word 'viaticum', meaning 'provisions for a journey'. This evolved into the Catalan word 'viatge' meaning 'journey', which was then borrowed into Spanish as 'viaje'. The verb 'viajar' was then formed by adding the common Spanish verb suffix '-ar' to 'viaje'.

This etymology shows how the concept evolved from a physical road or path (via), to the provisions needed for traveling (viaticum), to the journey itself (viatge/viaje), and finally to the action of making the journey (viajar).

Several common Spanish words share this same Latin root 'via'. The noun 'viaje' (journey) is directly related to 'viajar'. You might also recognize 'vía' (way, route), which preserves the original Latin meaning almost exactly. There's also 'viajero' (traveler) and 'enviar' (to send) which involves making something go on its way.

English has borrowed several words from the same Latin root 'via'. The word 'via' itself is used in English to mean 'by way of' or 'through'. You might also recognize it in words like 'viaduct' (a bridge for a road), 'viable' (capable of working or functioning), and 'deviate' (to move away from a path). The word 'voyage' is also related, having come from the same Latin root through French.