The Spanish word 'detestable' comes from the Latin 'detestabilis', meaning 'detestable' or 'abominable'. This Latin word was derived from 'detestari', meaning 'to curse or denounce', which was formed by combining two elements: the prefix 'de-' (meaning 'away from') and 'testari' (meaning 'to witness or testify'). The original concept behind 'detestari' was essentially 'to call upon witnesses to denounce something' or 'to curse while calling upon witnesses', which eventually simplified to just 'to denounce or curse'.

The evolution from a specific legal or ceremonial term involving witnesses to a more general word for something worthy of strong condemnation shows how words can broaden their meaning over time while maintaining their negative connotation.

Some related Spanish words include 'testar' (to make a will/testament) and 'testigo' (witness), which come from the same Latin root 'testari'. While 'detestable' evolved to describe something worthy of condemnation, these related words maintained meanings closer to the original sense of witnessing or giving testimony.

English speakers will recognize many cognates from this word family, including the identical word 'detestable', as well as 'detest', 'testify', 'testimony', and 'testament'. All these words share the Latin root 'testari'. While 'detestable' and 'detest' maintained the negative sense of condemning or disliking intensely, words like 'testify' and 'testimony' kept the original meaning related to witnessing or giving evidence.