The Spanish word 'deidad' (meaning 'deity') comes from the Latin word 'deitas', which meant 'divine nature'. The Latin 'deitas' was formed by combining two parts: the word 'deus' meaning 'god', and the suffix '-tat' which was used to form abstract nouns indicating a quality or state. So literally, 'deitas' meant the quality or state of being divine, which evolved into the modern Spanish word for a deity or god.

Some related Spanish words include 'dios' (meaning 'god') and 'divino' (meaning 'divine'), which share the same ancient root referring to divinity and godhood. While 'deidad' refers specifically to a deity or divine being, 'dios' is the more common everyday word for 'god'.

The English word 'deity' is a direct cognate of Spanish 'deidad', as both come from Latin 'deitas'. Other related English words include 'divine' and 'divinity'. While these words took slightly different paths through French and Latin, they all trace back to the same Indo-European root relating to gods and the divine. The word 'divine' in particular shows how this root evolved to mean not just 'godlike' but also 'excellent' or 'heavenly' in a more general sense.