The Spanish demonstrative pronoun 'eso' (meaning 'that') comes directly from the Latin word 'ipsum', which meant 'that' or 'this'. This is a clear example of how Spanish inherited and simplified many basic demonstrative words from Latin. The evolution from 'ipsum' to 'eso' shows typical sound changes that occurred as Latin evolved into Spanish, with the 'ip-' sound shifting to 'e-' and the '-um' ending becoming '-o'.

Other common Spanish words related to 'eso' include 'este' (this) and 'ese' (that). These demonstratives form a complete system in Spanish for pointing to things at different distances - 'este' for things close to the speaker, 'ese' for things near the listener, and 'eso' for things far from both.

While English 'that' is not etymologically related to Spanish 'eso', we can find a connection to Latin 'ipsum' in English words like 'ipso facto' (by the fact itself) and 'ipsum' as used in the placeholder text 'lorem ipsum'. These preserve the original Latin form in specialized or technical contexts.