The Spanish word 'mercado' (meaning 'market') comes from the Latin word 'mercatus', which also meant 'market'. This Latin word developed from the verb 'mercari' meaning 'to trade', which itself came from the Latin noun 'merx' meaning 'merchandise'. You can see how the concept of goods or merchandise led to the verb for trading those goods, which then developed into the place where such trading happens - the market.

Several common Spanish words share this Latin root, including 'mercancía' (merchandise), 'comercio' (commerce), 'comercial' (commercial), and 'comerciante' (merchant). All these words relate to the basic concept of trade and commerce that stems from the original Latin root.

Many English words are related to 'mercado' through the same Latin roots. These include 'merchant', 'merchandise', 'mercantile', 'commerce', and 'market'. The word 'market' is particularly interesting as it followed a similar path from Latin 'mercatus' through Old French to English, while 'mercado' developed from the same Latin word through Spanish. This is why 'market' and 'mercado' sound somewhat similar and mean the same thing!