The Spanish word 'comparsa' comes from Italian 'comparsa', which meant 'appearance' or 'extra/background actor in theater or film'. The Italian word developed from the verb 'comparire' meaning 'to appear', which in turn came from Latin 'comparere' meaning 'to appear or show oneself'. In Spanish, the meaning evolved to specifically refer to a group of people who participate together in carnival celebrations, as well as taking on the general meaning of 'companion'.

This semantic evolution makes sense when you consider that carnival participants and extras in theater both 'appear' or 'show themselves' as part of a performance or celebration. The meaning of 'companion' likely developed from the idea of people appearing or showing up together in a group.

A related Spanish word is 'comparecer', which means 'to appear' (especially in court or formally). Like 'comparsa', it comes from Latin 'comparere' and maintains the original meaning of 'appearing' or 'showing oneself'.

The English word 'appear' shares a distant connection with 'comparsa' through Latin. While 'appear' comes from Latin 'apparere' rather than 'comparere', both Latin words are formed from 'parere' (to come forth, be visible) with different prefixes. The English word 'compare' is also related, coming from Latin 'comparare', which is derived from the same 'com-' prefix and 'par' (equal) rather than 'parere'.