The Spanish word 'pollo' meaning 'chicken' comes directly from the Latin word 'pullus', which meant 'young bird' or 'chick'. The Latin word underwent a simple phonetic change where 'pullus' evolved into 'pollo', following common sound changes from Latin to Spanish where 'll' became a palatal sound.

A few related Spanish words include 'polla' (young hen) and 'pollito' (little chick), which are direct derivatives of 'pollo'. The diminutive form 'pollito' is particularly common when talking about baby chickens.

While English 'poultry' might look unrelated at first glance, it actually comes from the same Latin root 'pullus'. The word entered English through Old French 'pouletrie', ultimately derived from Latin 'pullus'. This shows how the same ancient word for young birds evolved differently in different languages while maintaining related meanings around domesticated fowl.