The Spanish word 'semáforo' (traffic light) comes from French 'sémaphore', which was constructed from two Ancient Greek elements: 'sema' meaning 'sign or signal' and '-phoros' meaning 'bearing or carrying' (from the verb 'pherein' - to bear or carry). So etymologically, a 'semáforo' is literally something that 'carries or bears a signal', which perfectly describes its function as a traffic signal that displays different colored lights to control traffic flow.

The word 'semáforo' is relatively unique in Spanish vocabulary and doesn't have many common, simpler related words. However, you might encounter the prefix 'sem-' or 'sema-' in other Spanish words related to signaling or meaning, such as 'semántica' (semantics) or 'semiótica' (semiotics), which share the same Greek root 'sema' for 'sign'.

English speakers might recognize this word's connection to 'semaphore', which refers to a system of visual signaling using flags or lights. Both the Spanish 'semáforo' and English 'semaphore' come from the same French word 'sémaphore'. Additionally, the Greek root 'sema' appears in English words like 'semantic' (relating to meaning), 'semiotic' (relating to signs and symbols), and 'polysemy' (having multiple meanings).