The Spanish word 'obispo' (meaning 'bishop') comes from the Latin word 'episcopus', which was borrowed from Ancient Greek 'episkopos'. The Greek word is a compound of two parts: 'epi-' meaning 'over, upon' and 'skopein' meaning 'to look or observe'. So literally, 'episkopos' meant an 'overseer' or 'supervisor' - someone who watches over others.

The evolution from Latin 'episcopus' to Spanish 'obispo' shows some typical sound changes: the initial 'e' changed to 'o', and the internal '-sc-' simplified to '-b-'. These changes made the word easier to pronounce in Spanish while maintaining its essential meaning of a religious overseer or bishop.

A related Spanish word is 'episcopal' (meaning 'relating to bishops or the church'), which maintains a closer resemblance to the original Latin form. Another related term is 'episcopado', referring to the office or tenure of a bishop.

English speakers might recognize this word's connection to 'episcopal' and 'Episcopalian', both relating to church governance by bishops. These English words preserve the original Greek spelling pattern more closely than the Spanish 'obispo'. The Greek root 'skop-' is also found in many English words like 'telescope' (far-looking), 'microscope' (small-looking), and 'scope' itself, all relating to viewing or examining.