The Spanish word 'atletismo' (athletics) comes from combining 'atleta' (athlete) with the suffix '-ismo' (meaning an activity or system). The word 'atleta' traces back through Latin 'athleta' to Ancient Greek 'athletes' (ἀθλητής), meaning a competitor or contestant. Going even further back, 'athletes' derives from the Greek word 'athlos' (ἆθλος) meaning contest or competition, which evolved from an earlier form 'aethlos' (ἄεθλος) meaning contest or struggle.

A simpler related Spanish word is 'atleta' (athlete), which is the base word from which 'atletismo' was formed. The suffix '-ismo' is very common in Spanish and is used to form nouns referring to activities, systems, or practices, similar to English '-ism'.

English speakers can easily relate this word to 'athlete' and 'athletics', which share the same Greek origin. The English and Spanish terms maintained very similar meanings, both referring to sports and physical competitions. The English word 'athlete' comes from the same Latin 'athleta' that gave Spanish 'atleta'.