The Spanish word 'frío' meaning 'cold' comes directly from the Latin word 'frigidus', which also meant 'cold'. Over time, as Latin evolved into Spanish, 'frigidus' underwent phonetic simplification, dropping the medial '-gid-' syllable and resulting in the modern Spanish form 'frío'.

Several common Spanish words are related to 'frío', including: 'resfriado' (a cold/flu), 'refrescar' (to refresh/cool down), and 'refrigerador' (refrigerator). All these words share the basic concept of coldness or cooling in their meanings.

English speakers can connect 'frío' to several familiar English words that come from the same Latin root 'frigidus', such as 'frigid', 'refrigerator', and 'refrigerate'. The connection is easy to remember since these English words all relate to coldness or cooling, just like the Spanish 'frío'.