The Spanish word 'concierto' (meaning 'concert' or 'agreement') comes from the Latin word 'concertare', which meant 'to contend with' or 'to dispute'. This Latin word was formed by combining two parts: the prefix 'con-' meaning 'together' and 'certare' meaning 'to contend' or 'to strive'. The Spanish verb 'concertar' developed from this, taking on the meaning 'to arrange' or 'to agree'. The Italian word 'concerto' also influenced the development of the Spanish 'concierto', particularly in its musical sense.

It's interesting to see how the meaning evolved from the idea of 'striving together' or 'contending together' in Latin to eventually mean an arrangement or agreement in Spanish, and specifically a musical arrangement in its most common modern usage.

A simpler related Spanish word is the verb 'concertar', which means 'to arrange' or 'to agree'. When you learn 'concierto', you can remember that it's essentially the noun form related to this verb - when musicians 'concertar' (arrange or agree) to play together, they create a 'concierto' (concert).

English speakers might recognize the connection to the word 'concert', which comes from the same Latin roots. Both the English 'concert' and Spanish 'concierto' share the idea of people coming together in harmony - whether that's musicians performing together or people reaching an agreement. The English word 'concerted' (as in 'a concerted effort') also comes from this same root, preserving the original meaning of people working or striving together.