The Spanish word 'compás' comes from the Latin verb 'compassare', meaning 'to measure with steps'. This Latin word was formed by combining two elements: the prefix 'com-' meaning 'together' and 'passus' meaning 'step'. The word evolved into Spanish 'compasar' meaning 'to measure', and then to 'compás', which now refers to both a compass (measuring instrument) and musical time/rhythm. This semantic development makes sense as both meanings relate to measurement - either physical space or time intervals in music.

A related Spanish word is 'paso' (step), which comes from the same Latin root 'passus'. You can also find this root in words like 'pasar' (to pass) and 'pasillo' (hallway, passage). The connection between these words and 'compás' lies in the basic concept of measurement through steps or movement.

Several English words share this etymology, including 'compass' (the measuring and navigational instrument) and 'pace' (which comes from Latin 'passus'). The word 'pass' and its derivatives like 'passage' are also related. You can see how all these words maintain some connection to the original concept of measuring by steps or movement.