The Spanish verb 'escuchar' (to listen) comes from the Vulgar Latin 'ascultare', which developed from Classical Latin 'auscultare'. The Latin 'auscultare' literally meant 'to apply the ear' and was formed from 'auris' meaning 'ear'. Over time, the Latin 'auscultare' simplified to 'ascultare' in Vulgar Latin, and then underwent sound changes to become 'escuchar' in Spanish, while maintaining its basic meaning of 'to listen'.

A related Spanish word is 'oreja' (ear), which also comes from Latin 'auris'. While 'escuchar' developed from a verb form meaning 'to apply the ear', 'oreja' developed directly from the noun for ear itself. Another related word is 'ausente' (absent), which originally comes from Latin 'absens', formed from 'ab-' (away) + 'sens' (being), from the same root that gave us 'escuchar'.

English speakers might recognize the connection to words like 'auscultation', the medical term for listening to internal sounds in the body (like a doctor using a stethoscope). This medical term preserves the original Latin 'auscultare' almost unchanged. The English word 'ear' is also distantly related, though it comes from Germanic rather than Latin roots.