The Spanish word 'pocho' comes from the Latin word 'putidus', meaning 'rotten' or 'decayed'. This Latin word evolved through Vulgar Latin, where a variant form with a short 'u' (*putidus) developed. As the word made its way into Spanish, sound changes transformed it into 'pocho', which came to mean 'discolored', 'rotten', or 'sickly'.

This evolution shows how the Latin 'u' sound shifted to 'o' in Spanish, and the medial 't' softened to 'ch', both common sound changes in the development from Latin to Spanish. The meaning remained fairly consistent, continuing to refer to things that are deteriorated or in poor condition.

A related Spanish word is 'pudrir' (to rot), which comes from the same Latin root. Another connection can be made to 'pudrición' (rotting, decay), which shares the same etymological origin and semantic field of deterioration and decay.

While English doesn't have any direct cognates from the Latin 'putidus', we do have some related words that entered through scientific Latin, such as 'putrid' (meaning rotten or decayed) and 'putrefy' (to make or become rotten). These words share the same Latin ancestor and carry similar meanings related to decay and rottenness.