The Spanish word 'pescadero' (meaning 'fishmonger') has its roots in Latin. It starts with the Latin word 'piscis' meaning 'fish', which evolved into the Latin verb 'piscari' meaning 'to fish'. This became the Spanish verb 'pescar' (to fish).

The word was then built up in two steps: First, adding the past participle suffix '-ado' to 'pescar' created 'pescado', which is actually the common Spanish word for 'fish' (literally meaning 'that which has been fished/caught'). Then, the occupational suffix '-ero' was added to 'pescado' to form 'pescadero', literally meaning 'one who deals with fish' - a fishmonger.

Several common Spanish words share this etymology and are easier to learn first: 'pescar' (to fish), which is a basic verb, and 'pescado' (fish), which is one of the most common food words. Understanding that 'pescado' literally means 'fished' or 'caught fish' (as opposed to 'pez' which means 'live fish') can help remember its connection to 'pescadero'.

While English 'fish' is not related to these Spanish words, there are some English words that come from the same Latin root 'piscis': 'piscine' (relating to fish), 'piscatorial' (relating to fishing), and 'Pisces' (the astrological sign of the fish). These formal English words are less common but show the same Latin origin.