The Spanish word 'equino' comes from the Latin word 'equinus', meaning 'of or relating to horses'. The Latin 'equinus' was formed by combining two parts: the root 'equus' meaning 'horse' and the suffix '-inus' meaning 'belonging to' or 'of the nature of'. This combination literally means 'belonging to or characteristic of horses'.

Some related Spanish words include 'equitación' (horseback riding), 'ecuestre' (equestrian), and 'equipo' (team, equipment - which originally referred to equipment for horses and their riders). These words all share the Latin root 'equus' for horse, though their meanings have evolved over time.

English speakers might recognize the connection to words like 'equine' (relating to horses), 'equestrian' (relating to horseback riding), and 'equitation' (the art of horseback riding). All these words share the same Latin ancestor 'equus'. The English word 'equine' is a particularly close relative, as it comes from the same Latin word 'equinus' as the Spanish 'equino'.