The Spanish word 'reloj' (meaning 'clock') has an interesting journey from ancient Greek roots. It comes from the Greek word 'horologion', which literally meant an 'hour-telling instrument'. This Greek word was formed by combining three parts: 'hora' (meaning 'hour'), 'legein' (meaning 'to speak or tell'), and '-ion' (a suffix used for instruments).

The Greek 'horologion' was borrowed into Latin as 'horologium', where it referred to sundials and water clocks. This Latin word then evolved through Old Catalan 'relotge' before finally becoming 'reloj' in Spanish. The transformation from 'horologium' to 'reloj' shows how words can be significantly shortened and altered as they pass through different languages over time.

A related Spanish word is 'hora' (meaning 'hour'), which comes directly from the same Greek root 'hora' that forms part of 'reloj'. This connection makes sense since a 'reloj' is literally an instrument for telling the 'hora' or time.

English speakers might recognize this etymology in words like 'horology' (the study of time and timepieces) and 'horological' (relating to clocks or watches). These English words preserve more of the original Greek form than Spanish 'reloj' does. The 'hor-' element is also found in English words like 'hour' and 'hourglass', all ultimately relating to time measurement.